Project managers vs Product owners

I frequently come across discussions on the internet about using project managers as product owners in Agile projects.

These discussions often spring out of discussions on what the role of a traditional project manager is in an Agile project, and since project managers often prioritize work in traditional projects, it makes sense to think of using them as product owners, who, after all, should prioritize the work that the developers do.

I disagree.

When Scrum was created, and the roles of Scrum Master and Product Owner came into existence, the people who got those roles, were the traditional project managers - at least according to what Jeff Sutherland said when I got my Scrum Master certification at his course.

That probably made sense back then, but I think it is a bad idea to do so now, for several reasons.

First, and foremost, I think it is a bad idea, because you need the project manager to focus on the project and its priorities. Unless you run an extremely agile project, there is still a need for a project manager taking care of the non-development aspects of the project (e.g. resource planning, dependency management with other projects, and other tasks ignored by Scrum and other Agile methods). In other words, project managers need to focus on the restraints and barriers of the project, and ensure that these doesn't affect the project and its progress.

Product owners, on the other hand, should represent the business/customers, ensuring that they get the most value out of the project as they can, within the boundaries set by the project manager.

Secondly, I think the skillset required to be a good project manager is orthogonal to the skillset required to be a good product owner, and it is best to use people in the role they fits the best.

A good project manager is good at forecasting and evaluating risks for the projects, ensuring that the people inside the project can perform optimally. A good product owner, on the other hand, understands the needs of the business/customers, and can translate this in a way that the developer team (including testers) can understand. This is why good product owners often are business analysts with a developer or tester background.

Thirdly, in most projects, being a product owner is a full time job. The number of developers in a project generally outnumbers the product owner by a fair margin, and having the product owner do project management as well, will slow the project down - or at least limit the number of developers that can be in the project.

All of the above is based on the premise that projects still need project managers, even if the development process (e.g. Scrum) doesn't call for it. If that's not the case, then the only relevant objection is my second point, about the necessary skillset being quite different. But this is a major point! In my experience, the role of the product owner is essential for the success of an agile project, and all too often, the selection of the product owner is taken too lightly.

If you want to find a good place for your project manager, look at the Scrum Master role, which has many similarities, focusing on sheltering the developers and create the framework for the development process.