I once worked for a startup co-founded by people who created DirectX at Microsoft. There is a book written on how DirectX was created and what went on inside the team during those initial days of DirectX. Hence this book was available in the library of the startup where I worked. These is a very interesting statement in that book on the topic of what a manager's responsibility should be in a team. And this is what it said:

"A manager's responsibility is to remove any roadblocks from the path of an engineer. If an engineer is coming down a hallway and there is a chair in the path blocking that engineer, then it is the manager's responsibility to remove the chair from the path so that the engineer is not troubled." :)