I've always used a signal processing analogy for management communication. "Managers are lossy, high trasport-delay, filters." Any time a manager is between two people trying to transer information, there will be delay, and there will be information dropped.
Now, sometimes, that is a huge benefit. Not everyone can know everything in any organization of reasonable size, so there is benefit to having someone summarize information from other areas that I need to be aware of, and communicate only the bits that are relevant to me. OTOH, there are times when the best way to accomplish a particular mission is to get the manager out of the communication path so that the people with the expertise can communicate directly, at full speed and full fidelity, and deliver a solution.
So to me the litmus test for a manager is: "Am I adding value by filtering this information?" If no, then get out of the signal path.
And just like good technicians (and practitioners in most disciplines), when we're doing the best work, it hardly looks like we're doing anything at all - which is hard to distinguish from managers who are hardly doing anything at all!
The full philosophy can be seen in Dan Pontefract's "Flat Army"
http://www.danpontefract.com/the-book/