I often meet people who are transitioning to agile, and they decided to pick Scrum, because it's a helpful project management framework. Ok, that makes sense. But then they decide that they no longer need project managers, and that the development manager can act as the Scrum Master.
The Scrum Master is not a management position. The Scrum Master protects the team's process and removes the team's obstacles. For me, the Scrum Master is analogous to the project manager. (I've never believed in command-and-control PMs.)
There is still a need for managers, but a little differently. I don't see the need for functional managers. The agile team needs a manager who champions that whole team. That means that the champion managers need to understand all the functional parts in the team, so they can help each team member.
But the real issue is that it's a bad idea to have a manager be a Scrum Master. Here's why:
- The Scrum Master is a part of the team, and the manager, because of his/her titular authority can never be a part of the team.
- People are reluctant to take a risk in front of their managers. (Bob Sutton in Weird Ideas That Work: How to Build a Creative Company cites data about this.)
- Managers set direction, which is more strategic work. They do this with managing the project portfolio, looking at the makeup of the teams, seeing if they need more people. Scrum Master work is tactical, about the day-to-day work of the project team. If you have to choose between strategic work and tactical work, which one will win? (Tactical, all the time.)
So what does happen to the managers when an organization transitions to agile? They help teams self-organize. They manage the project portfolio. They provide feedback and coaching. They champion the team. They take the lead on hiring.
Managers, do your management job. Project teams, including the Scrum Master, do your project work. The two types of work intersect above the project, not in it.