I guess I'm missing something. Is the coach successful or not?
If so how do argue against success? If not then it is the responsibility of the AD to make a change.
If the coach is not playing the best lineup the proof will be in the won-loss record.
That's the information that gets conveniently left out of virtually every "School ball is terrible" post I see anywhere on the internet (along with all the missing footage of the kids playing lights-out better than whoever is playing ahead of them).