I have been doing this a very long time in computer terms. I have worked for both clued and clueless managers. Been one or the other a few times. But the end all and be all of IT managment is getting the work done. I don't know how anyone successfully does that unless they know what their primary resource is capable of and what the problems and limitations of their chosen tools are.

Managers who are not the absolute best worker on a team, in my experience, are only sucessful when surrounded by superstars and have the maturity to be an enabler, not a manager. These people basically are super gofers, providing support for a team, and then getting out of the way. The problem comes in when the team hits a wall and needs guidance. Without indepth knowledge, the team has nowhere to go except outside. Very expensive, and time consuming.