Head Coach has almost all of the control. Im sure there are cases where the AD acted against a coach's wishes but it'd be pretty rare... The final paperwork is signed by the AD, but the coach decides.
Sure they're going to listen to the coach but in the case of Sanderson, he wasn't the coach, wasn't even an employee of the university. He had no input into the decision.
As for AD's being lenient with their lease, tell that one to the Iowans that were saddled at Virginia Tech.