At the end of January I’m running my 1-day Requirements, User Stories and Backlogs workshop in London with Learning Connexions. I get great feedback from people who attend the course, perhaps because it is mostly exercised based.
If your interested check out the Learning Connexions page – its just one day and won’t break the bank! Hope to see you there.
I feel compelled to write this blog because I keep coming across the wrong type of Product Owner. I feel bad about writing this blog because a) I’ve made these points before in other forums so I’m repeating myself, and b) at the end of the day you, your team, and your organization, is free to define and use any title you like for any role you like, you are free to define any given role as you like.
So let me set out my model of a Product Owner and then at least there is a model to compare any other definition with.
Our old friend the Triangle of Constraints can help here – also know as “The Iron Triangle” and pictured above (I like to call it the FRT triangle). Now notice the version I use is slightly different from the more common model:
Rather than “cost” I label one side of the triangle “People”. I could label it resources but in software development resources are overwhelmingly people and the knowledge they bring. People deserve respect, calling them “resources” makes them sound like paperclips.
For software development costs are function of how many people you have and how long you have them for: costs = people x time. OK, there are some other “resources” to add to costs, e.g. buying laptops, renting time in the cloud, and so on but these are often themselves a function of the number of people you have. Such costs are a small increment on top of the wage bill.
Now the number of people you have is fixed in the short term, or to be more accurate: it is upward fixed. People can get ill or resign at anytime but adding people takes time. So in the short run one can consider that dimension fixed.
Time is also fixed. There is usually a business deadline, or rather a business benefit which is time elastic so you have a date to aim for. And on agile teams there are sprint deadlines (two-weeks, two-weeks, two weeks). So a large part time is fixed.
The final side of the triangle is labelled features or functionality, but might be labelled “requirements”, “the what” or “what are we building” – I like to think of it as the demand side.
With me so far? – so far that should be uncontroversial.
Now the traditional Project Manager role, and to a lesser degree the newer Delivery Manager role, tend to regard the third side – the what side – as fixed. There is a thing to be delivered. It is a known thing. It has been decided on and the manager’s job is to get it delivered.
To this end Project Managers are trained to regard the “thing to be built” as a given, preferably fixed, thing. Their training centres on the other sides: cost and time. They are trained both in rationing these commodities and allocating them in an efficient way. When things go wrong these managers ask for more time (which means more money because the same people need paying) or more people (which both costs more and makes things worse because of Brook’s Law).
So to summarise: traditional Project Managers focus on “when” and the input variables: people/resources and money.
Can you guess what I’m going to say next?
Product Owners – plus Product Managers and Business Analysts – focus on the “what”. What do we need to build next? What has the most benefit? What should we be building for the future?
For Product Owners the time and people are fixed. (This is most obvious in an agile environment but is actually true everywhere sooner or later.)
The thing being built is negotiable, the desired outcome may be achieved by different routes, different technologies and different solutions – the different time and cost will be a consideration but outcome is the primary focus.
In other words: Product Owners are all about the what.
In order to operate in the what-space product owners need authority and legitimacy to flex what they are building. When they don’t have that they are reduced to backlog administrators simply ordering the backlog and feeding it to technical teams. That turns the role into a type of Project or Delivery Manager.
So if you need to tell a real Product Owner from all the other misinterpretations of the role ask:
Does the product owner focus on what?
Can the product owner discuss different solutions and approaches to achieve an outcome?
Is the PO flexible about the backlog? (as opposed to slavishly trying to deliver it all)
Real product owners can answer Yes to all three.
(Notice I’m deliberately being careful in what I say about “Delivery Managers.” This role is still emerging and as such its wrong to generalise about it too much. In so much as a Delivery Manager brings management skills, communication and organization to an effort it can be a positive role. When a Delivery Manager is relabelling of the Project Manager role it can be damaging.)
Now that said, the fact that some organizations choose to define the “Product Owner” role as a role closer to “Project Manager” or “Delivery Manager” rather than a role closer to “Product Manager”, “Business Analyst” or (heaven forbid) business owner causes a lot of confusion.
Perhaps I’m wrong here, perhaps the “Product Owner” is a type of “delivery manager” but I think the majority of writers, thinkers and practitioners agree with me.
Even if you disagree with me I hope we can agree on one thing: because there are different interpretations and implementations of the role there is room for confusion; and that confusion makes it harder to fill the role and harder to be seen as a successful Product Owner.
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Is the product owner role impossible to fill well?
Do we set product owners up to fail?
Have you ever worked with a really excellent product owner? Someone you would be eager to work with again?
The lack of really outstanding product owners isn’t the fault of the individuals. I think product owners are asked to do a difficult job and are not supported the way they should be. Worse still, in many organizations the role of product owners is misunderstood, they are seen as a type of delivery manager when in fact they are a type of product owner.
There questions have been on my mind for a while, next month I’m giving a new presentation I’m Oredev in Malmo – and which coincides perfectly with the publication of my new book The Art of Agile Product Ownership (funny that). So by way of preview…
1. Skills: the kind of thing a product owner learns on a Certified Scrum Product Owner course are table stakes. Yes POs need to be able to write user stories, split stories, write acceptance criteria, understand agile and scrum, work with teams, plan a little and so on. While necessary such skills are not sufficient.
The bigger question is:
How does a product owner know what they need to know in order to do these things?
How do they know what customers want?
How do they know what will make a difference?
Product owners need more skills. Some POs deliver products which must sell in the market to customers who have a choice. Such POs need to be able to identify customers, segment customers and markets, interview customers, analyse data, understand markets, monitor competitors and much more. In short they need the skills of a product manager.
Other POs work with internal customers who don’t have a choice over what product they use, here the PO needs other skills: stakeholder identification and management, business and process analysis, user observation and interviewing, they need to be aware of company politics and able to manage up. In other words, they need the skills of a business analyst.
And all POs need knowledge of their product domain. Many POs are POs because they are in fact subject matter experts.
That is a lot of skills for any one person. How many product owners have the right skills mix? And if they don’t, how many of them get the training they need?
2. Authority: Product owners need at least the authority to walk in to a planning meeting and state the work they would like done in the next two weeks. They need the authority to set this work without being contradicted by some other person, they need the authority to visit customers and get their expenses paid without having to provide a lengthy explation every time.
3. Legitimacy: Product owners need to be seen as the right person to set the priorities. The right person to visit customers, the right person to agree plans and write roadmaps. They need to be seen as the right person by the organisation, by peers and, most importantly, by the development team.
Authority and legitimacy are closely related but they are not the same thing. While the product owner needs both the lack of either results in the same problem: people don’t take their work seriously and other people try to set the agenda on what to build.
Unfortunately Scrum contains a seldom noticed problem here: product owners are team members, they are peers; the team are self organising and are responsible for delivering the product. (There is an egalitarian ethos even if this is only Implicit.)
But Scrum sets the PO as the one, and only one, who can tell he team what to do.
There is a contradiction.
4. Time: Product owners need time to do their work – which is a lot, just read that skills list and think about what the PO should be doing. And don’t forget the PO is a human being who needs to sleep for seven or eight hours a night, may well have a family and a home to go to.
When does the product owner get to do all of this?
Leave aside the question of where you find such people, or whether our companies pay them enough and ask yourself: do product owners get the support they need from their companies and teams?
So often the PO ends up in conflict with the company about what will be built and when it will be delivered, and they end up in conflict with their team about… well much the same issues every planning meeting.
Think about it: do we ask too much from our product owners?
Do we set up product owners to fail?
I’d love to hear your opinions, comment on this post or drop me a note or leave a comment.
As regular readers might know I’m working on a book called The Art of Product Ownership to be published by Apress later this year. One of the chapters is entitled “Why have a Product Owner” and a few days ago a bunch of ideas crystallised into this…
The aim of the Product Owner is to increase, even maximise, the business value delivered by the team as a whole. The Product Owner does not so much create value themselves as increase the value created by others.
Think of it like this: if the team randomly selected work to do and delivered it to customers then some value would be created. (For the moment I’ll ignore the scenario where that work detracts from the existing value.) The aim of the PO is to ensure the work done creates more value than a simple random selection. The greater the difference, or delta to use a mathematical term, between random selection and an informed selection the better.
The general hypothesis is that intelligent selection of work by a skilled Product Owner will result in both more value being delivered and an increasing delta between intelligent PO selected work and randomly selected work.
This difference the value added by a Product Owner. I like to call this difference the Product Owner Delta.
Now in real life work is seldom randomly so Product Owners are not competing against random selection. In some cases the alternative to a designated Product Owners is someone else: a senior developer, an architect, a manager or someone else. In such cases this person is taking on the Product Owner role. They may not have the title, the aptitude, the skills or official position but when work is selected by one person they are de facto the Product Owner.
In other cases the alternative to the PO might be selection by consensus on the team, or a sub-set of the team. Now it is entirely possible that such a group could outperform a single Product Owner in selecting work – especially is they have market and customer knowledge, some analysis skills, time to do the background research and so on. In some cases this works, for example think of a small start-up staffed by software developers creating software development tools.
However, in some cases selection by committee might be inferior to a random selection. Imagine a team which has never met a customer, argue about what to do, duck key decisions and never say No to any request. Its easy to image a dysfunctional selection committee.
There is more to increasing the Product Owner Delta than simply selecting the highest value items. Timely selection can help too. If decisions are not being made, or committees are spending a long time making decisions then having one person simply make those decisions in an efficient, timely, manner can increase the delta.
Time has another role. Because of cost-of-delay simply selecting the highest value items at any one point in time does not maximise the value delivered. Time Value Profiles (see Little Book of User Stories or my presentations on value “How much? When?”) expose this and need to be another tool in the Product Owners repertoire.
And of course, the Product Owner Delta is not the only reason to have a Product Owner in the team, but it is probably the main reason.
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Recently I’ve been looking again at Jobs to be Done and OKRs (Objectives and Key Results). I increasingly see them as story generators and a potential solution to the tyranny of the backlog I described last time.
When I first looked at Jobs to be Done (and OKRs actually) I wondered if they constituted a fourth, top, level on top of Epics, Stories and Tasks. I’ve long argued against having more than three levels of things to do (or requirements as we used to call them.) There are big meaningful things to do (stories), really big things which we don’t as yet understand but look really valuable (epics) and the immediate small things to do right now (tasks).
Actually, I’d rather think most things can be dealt with by two levels and one level is the even better. So adding a fourth “even bigger” thing on top of Epics just felt wrong. Technologists (like myself) have a tendency to map everything into hierarchies; inverted trees with fractal like branches. But not everything is, or should be, a hierarchy, mapping the world into a tree like structure can add complications.
Unlike stories (and epics and tasks) Jobs to be Done don’t really lend themselves to the transactional “Done”. While you could put a Job all the way to Done on your Kanban board and track it from “To do” to “Done” in reality the customer job still exists. Sure you’ve improved it but you can improve it again – another example of Stable Intermediate Forms. This seems to be the great potential of Jobs to be Done, they keep on giving: as much as you improve your product to help with the job you can still improve it some more.
So each time you analyse the Job to be Done you should be able to find more stories to deliver to improve it. Hence the Job to be Done is not a “story” to do, it is a Story Generator. Every time you look at the job to be done you find more stories, every time you examine the result of the latest improvement you find more stories. The job will never be done. Some might see that as a bad thing but that also means the job presents a stable focus for ongoing work.
The same might be true of OKRs but in a slightly different way. Because the objective is reviewed periodically – every quarter or so – it lacks the continuity of Jobs to be Done but perhaps allows the team to switch targets, maybe it is stable enough.
The key results may well be stories in their own right, or they may be things which lead to stories. Either way one can expect some key results to be achieved and marked as done regularly. As they fall they are either replaced by new key results building towards the objective (which themselves lead to stories) or new key results are added for new objectives.
I’m sure there are other story generators out there but the key thing for me is not the mechanism but the existence of the generator. Once you have a story generator you do not need a big backlog of things to do. The generator will replenish the backlog whenever you need more stories – either because you have done them or the value has fallen.
Using a generator removes the need to have a big backlog which removes the tyranny of the backlog. The team are now free(r) to concentrate on delivering value towards their objective.
Finally, I wonder if anyone has used both OKRs and Jobs to be Done together? Right now they feel like alternative generators to me, having both seems like a bit like overkill. Although I accept that maybe OKRs are more corporate and Jobs to be Done are more product focused. Anyone got any experience using them together?
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The backlog is a great idea: all the things we think the team will build, or perhaps: things they might build, and it might contain other work, like evaluation or reviews. Yes, the backlog is a great idea, all the stuff the team might do, well perhaps not all, it is seldom complete, after all, as they say “stuff happens”.
The truth is: backlogs have a tendency to grow. All too often I find teams who are struggling under the weight of their backlog. They can’t spare time to do experiments or learn something because there is stuff to do. The backlog becomes a tyrannical ruler and all of it MUST BE DONE.
Look at that hypothetical burn-down chart above. By sprint 15 the team is well on its way to completing all the original work. But the amount of work they need to do is higher than when they started. It is not as if the team have been doing nothing. Look at the next chart, it shows how, most weeks, more work is added than is done.
To my mind finding more work isn’t a problem, indeed teams should be finding more work. Problems stem from the fact that backlogs – and tracking mechanisms like burn-down charts – try to full-fill competing needs.
The backlog is used as a store of ideas for work to do. This makes sense, you can’t do everything today so postpone some to the future. A backlog allows you t move some things from peak time to off-peak, although software development teams rarely seem to see off-peak time.
Plus, having a backlog makes it easier to say:
“Thanks for your suggestion Fred, I’ve added it to the backlog, I’ll let you know when we get to it.”
“Thanks for your e-mail Fred, we deleted it once we stopped laughing.”
It makes sense to give a new idea a quick once-over. But doing a proper analysis is time consuming:Discussing what is being asked for takes time, as does setting acceptance criteria are. And then there is business value to assess and other work priorities to consider. Therefore, put it in the backlog and do all that later (if it ever gets scheduled.)
Without a backlog we would be forced to make a binary decision: do it and do it now or reject it.
In fact the backlog can become a natural filter: as stories age in the backlog some items will jexpire. Unfortunately many Product Owners don’t feel they have the authority to delete old requests so the backlog grows and grows.
I call such a “constipated backlog”: work goes in but very little comes out. When the only way for items to leave the backlog is by doing them the rate of return falls.
The backlog fills another role because so many teams are still expected to meet project success criteria which ask for “everything to be done.” The backlog becomes a tyrant when people believe that one day it will all be done. Worse still, some people plan using this assumption.
People want to know when “it” will be done, how long it will take and how much it will cost. It takes time to answer those questions and if the backlog is growing any answer is going to be wrong.
In fact, it is probably wrong to think everything will ever be done. Unless one freezes the backlog and refuses to add new work then it is likely that low value items will be postponed while new, more valuable items, will take priority.
As an industry we need to drop the idea that a backlog will ever be done: the backlog as repository of ideas is at odds with the backlog as a measure of completeness.
Think about it this way: some of the items in the backlog are very valuable. Some items are worth very little. Some will cost more effort than the benefit they bring. If we do everything then the low value and the high value will all get done. Conversely, if we encourage new ideas and weed-out as many low value items as possible our rate of return will be higher.
But very few teams follow this model. Many more teams are slaves to the backlog, and their quest for an empty backlog is doomed.
I’m surprised to find I’ve written over 60 pages so far! Still, this is very much a work in progress, there are a few more chapters to add to part 1: The Product Owner role.
But it is part 2 which I’m itching to start writing: the tools of the trade.
For those who don’t know, the beauty of LeanPub is that you can buy my unfinished book now and you will receive updates – to your iPad, Kindle, PC, whatever – as they are produced.
That means three things to me.
Firstly I can receive your feedback – what do you like? What did I get wrong? What else should be in there?
Second, money is feedback, the more of you who buy the book the more motivated I am to write it – I like seeing sales, it tells me people want this book. And if you don’t buy… well maybe I should pivot and abandon it.
Third, it gives me a little beer money.
The bad news is: you also get my dyslexic spelling and grammar.
With some final words I’d like to draw this mini-series on the Product Owner to a close and open a new chapter with a new book. I’ve written six blog posts in the last two months and I have drafts for more but there are other things I want to blog about.
I have drafts for more posts and ideas for even more. So its time to make this into another book: Product Ownership. This is on the LeanPub site now and you can buy it. So far it just contains a new prologue story but I’ll add these posts soon as the first chapters.
Ever since I wrote Little Book of User Stories I’ve thought there should be a companion volume: “Little Book of Product Ownership”. The intention is for the first part of the new book to discuss the product owner role – and whether it should even exist – and then quickly get into the tools of Product Ownership.
Now some closing words…
While I’ve suggest a lot of things that a Product Owner should do, and a few that they should not do, there are really no hard and fast rules about what a Product Owner should or should not do.
In the language of business schools: there is no contingent way of being a product owner, every product owner and organization is different and they need to find their own path. I cannot give you a flow chart for what a product owner does or should do, nor can I give you a set of rules to say “When the customer says Foo the Product Owner should do Bar.”
Every Product Owner has to work out what is right for them because every organization is different. And every organization will – rightly or wrongly – expect different things from the people it christens Product Owner.
Additionally every team is different and contains different skills and experience. As a result every team will differ in what it needs from the Product Owner(s) and how the team members can support the Product Owner and share the work.
And every Product Owner is themselves different and brings different skills, experience and insights to the role.
Job #1 for a newly appointed Product Owner is to sit down and decide what type of Product Owner they are expected to be and what type of Product Owner they want to be:
They may be a Backlog Administrator taking instructions from others.
They may be a Subject Matter Expert using their expert knowledge of the domain to decide what the right product to build is and help other team members understand the details of what is being built.
They may need to analyse internal process and business lines using the skills of Business Analysis.
They may need to get out on the road to meet customers – and potential customers – to understand the market and where the opportunities are using the skills of Product Management.
They may need to call on skills from other fields to: Project Management, Consulting and Entrepreneurship to name a few.
But a Product Owner is not some other things:
If they were a developer they need to accept they will not be coding any more. There simply isn’t time and anyway, they need to trust the team.
If they were a Project Manager, Development or Line Manager they need to resist any urge to tell people what to do or look too far into the future. They need to re-focus on value not time, and recognise that their authority comes from their competence not from a position on a chart.
Product Owners from a Business Analysis background need to look beyond Business Analysis, specifically they need to immerse themselves in the world of Product Management.
While Product Owners who were Product Managers probably have the easiest ride they too need to change, they need to think more about internal stakeholders, processes and delivery.
Every Product Owner and everyone working with Product Owners needs to read and reflect on the role. Hopefully some of the words in my recent posts – and the new book – will help with that – and hopefully some of you might like to hire me for advice or a training course – just call
Finally, I sincerely believe there are better Product Owners and not-so-good Product Owners, and that some organizations (teams, companies, enterprises) which offer a better environment for Product Ownership and equally there are those which are downright hostile to product ownership.
Surprisingly I’ve never blogged about the Strategic Product Owner / Tactical Product Owner model, this is surprising because it is a model I both find again and again and advocate again and again.
I find lots of companies who have a version of this model in place, they have created the model to deal with their own situation. But few of these companies realise that this is a reoccurring solution and is quite legitimate. (I should write it up as a Pattern but I haven’t written any patterns for a while.)
More importantly I find that many companies and individuals faced with problems around Product Owners benefit from adopting this model. Specifically, as I’ve already mentioned there is a lot of work for a Product Owner to do and one way of doing this is to share the load.
If I were to write this up as a pattern the thumbnail version would say something like:
The Product Owner lacks the time – and sometimes skill – to fill the role fully therefore split the role in two. One person, the SPO (Strategic Product Owner), looks long term, they focus on customers and strategy. The other, the TPO (Tactical Product Owner), focuses on the near term (this sprint, the next sprint, the next quarter). The TPO spends most of their time with the delivery team while the SPO spends most of their time with customers and senior stakeholders.
Sometimes the Product Owner lacks time simply because – as I’ve said before – there is so much work the Product Owner should be doing they simply don’t have time.
Sometimes they lack time because the team is large, or the team lack domain knowledge (and therefore need to ask the PO lots of questions). Sometimes POs need to travel a lot to meet customers and even the most talented PO can’t be in two places at once.
They may also lack time because they have another job to do. While I think the Product Owner role is a full time job sometimes the person who is the right person to hold the role – usually because they command authority – needs to combine the work with another role.
For example, on a trading desk the Product Owner should probably be a senior trader who both knows the domain and has the authority to say Yes and No to features. But by definition such a person lacks time. Normally I’d want a dedicated Product Owner in place but sometimes the only way to have the necessary authority is to have another job.
And sometimes the person who is should be Product Owner – think our trader again – lacks the skills and experience to do the role. So again they need help.
The key thing about the SPO/TPO model is that the two people who hold the role need to speak with one voice. If they do not then the model will fail. Ideally the SPO will stand in when the TPO is unavailable and vice verse.
There is another occasion when the SPO/TPO model can be useful: big teams.
Ideally there is one product owner, one team and one stream of work. But sometimes there are several products, teams and streams. Here you might have an SPO who looks at the long term and several TPOs each of whom works with one team on one stream.
Now, like all good patterns this one is not without its downsides…
I’ve heard Scrum-advocates argue against this model: One True Product Owner they say. And they have a point… putting more people between the delivery team and the customer does detract from communication.
One of the problems software development faces is when multiple people think they have the right to say what is built next. Another problem occurs when the customer is remote from the development team and multiple people mediate what is asked for.
Ideally developers can talk to customers directly but that is often not possible or desirable – I won’t go into the reasons right now. So a good solution is One True Product Owner.
But then the One True Product Owner becomes a bottleneck so we split the role SPO/TPO. Yet every-time we introduce another link – another person – between the coders and the customer the greater the propensity to introduce problems. So it becomes a balancing act.
Nobody in between is the can be ideal.
One person can make it better.
Two people can be an improvement over one.
Three… I need some convincing this is an improvement over two.
Four… I find it hard to believe that having four people mediate the voice of the customer is an improvement… unless of course you previously had five!
For years I have been using this picture to describe the Product Owner role. For years I have been saying:
“The title Product Owner is really an alias. Nobody should have Product Owner on their business cards. Product Owner is a Scrum defined role which is usually filled by a Product Manager or Business Analyst, sometimes it is filled by a Domain Expert (also known as a Subject Matter Expert, SME) and sometimes by someone else.”
In telling us about the Product Owner Scrum tells us what one of these people will be doing within the Scrum setting. Scrum doesn’t tell us how the Product Owner knows what they need to know to make those decisions – that comes by virtue of the fact that underneath they are really a Product Manager, BA or expert in the field.
In the early descriptions of Scrum there was a tangible feel that the Product Owner really had the authority to make decisions – they were the OWNER. I still hope that is true but more often than not these days the person playing Product Owner is more likely to be a proxy for one or more real customers.
I go on to say:
“In a software company, like Microsoft or Adobe, Product Managers normally fill the role of Product Owner. The defining feature of the Product Manager role is that their customers are not in the building. The first task facing a new Product Manager is to work out who their customers are – or should be – and then get out to meet them. By definition customers are external.”
“Conversely in a corporate setting, like HSBC, Lufthansa, Proctor and Gamble, a Product Owner is probably a Business Analyst. There job is to analyse some aspect of the business and make it better. By definition their customers are in the building.”
With me so far?
Next I point out that having set up this nice model these roles are increasingly confused because software product companies increasingly sell their software as a service. And corporate customer interact with their customers online, which means customer contact is now through the computer.
Consider the airline industry: twenty years ago the only people who interacted with airline systems from United, BA, Lufthansa, etc. were airline employees. If you wanted to book a flight you went to a travel agent and a nice lady used a green screen to tell you what was available.
Today, whether you book with Lufthansa, SouthWest or Norwegian may well come down to which has the best online booking system.
Business Analyst need to be able to think like Product Managers and Product Managers need to be able to think like Business Analysts.
I regularly see online posts proclaiming “Product Managers are not Product Owners” or “Business Analysts are not Product Owners.” I’ve joined in with this, my alias argument says “they might be but there is so much more to those roles.”
It makes me sad to see the Product Manager role reduced to a Product Owner: the Product Owner role as defined by Scrum is a mere shadow of what a good Product Manager should be.
But the world has moved on, things have changed.
The world has decided that Product Owner is the role, the person who deals with the demand side, the person decides what is needed and what is to be built.
I think its time to change my model. The collision between the world of Business Analysts and Product Managers is now complete. The result is an even bigger mess and a new role has appeared: “Digital Business Analyst” – the illegitimate love child of Business Analysis and Product Management.
The Product Owner is now a superset of Product Manager and Business Analyst.
Product Owners today may well need the skills of business analysis. They are even more likely to need the skills of Product Management. And they are frequently expected to know about the domain.
Today’s Product Owner may well have a Subject Matter Expert background, in which case they quickly need to learn about Product Ownership, Product Management and Business Analysis.
Or they may have a Business Analysis background and need to absorb Product Management skills. Conversely, Product Owners may come from a Product Management background and may quickly need to learn some Business Analysis. In either case they will learn about the domain but they may want to bring in a Subject Matter Expert too.
To make things harder, exactly which skills they need, and which skills are most important is going to vary from team to team and role to role.