be plenty of other reasons to fire someone besides incompetence.

Craig Smith was fired at U of U not due to incompetence, but because they had another candidate in waiting who they wanted more.

Based on official news released by BYU about Coach Whiting not being retained, how would you even know whether it was a firing or a contract not being renewed? All that the official news said was that BYU and Coach Amber have agreed to part ways. If BYU chooses not to employ her as coach, what other decision does Amber have then to agree and move on with life. Does she have a choice to disagree with the BYU decision and to continue coaching?

And I still don't think you made your point about how it relates to what the AD thought about Coach Whiting's coaching. If they thought she was a great coach, they would have offered her a new contract. They didn't offer her a new contract (or at least that is what information has been spread here on cougarboard) which I understand to be because they thought she is an average or subpar coach.