A lot of benefit that I add in my day job is bridging the gap between high level folks (OS people) and what's-actually-happening-on-the-wire.

While so, so, so much of this is rarely the network, knowing how to look under the covers and see what's actually hitting the wire (versus what the API call asked for) leads to far, far faster resolution of problems.

It's frustrating to me that so many people see this as a mystery of "knowing networking" when it's really just basic protocol analysis.