Teaching is certainly an important skill an assistant should bring to the table. Folks are always referencing how a HC may need help with Xs and O's. I take that to mean a particular HC lacks some understanding as opposed to an ability to teach.
I'm obviously being naive here but we're talking about a sport where you only have five guys playing at one time. How can someone who is middle aged and has played or coached their entire life, need help with X's and O's?