Good managers know how to lead their staffs even if they can't do the grunt work.
There are a couple schools of thought out there regarding how much a manager should know about the intricacies of the actual work his or her team does. Management purists believe that if you have the best leadership skills, you don't need to understand the details of what your team does. Others think that if a manager doesn't get in there and dig ditches with the rest of the team, then he or she couldn't possibly understand how to represent that team to upper management.
I can see where the latter point of view might come from. I believe leadership skill is a talent by itself. I've known many people who were promoted from within teams who ended up not having what it took to guide that team.
Some people believe that managers should know how to do the grunt work so they can better judge bandwidth and better understand what tools a team needs to get the job done.
Of course, the ideal person would have both leadership skills and intimate knowledge of the team's duties. The best leaders understand what their teams do, without having to actually get in there and write code themselves. They also have a "world view" of what the company needs from its staff to grow.
What do you think?