Given Anae's resume, that he had come in and produced five straight years of good to great offense for BYU, he didn't deserve to be told he had to reapply for his job just because of one down season.
Though in hindsight it seems Anae was frustrated with things he wasn't allowed to control during his first stint, like who his assistants were, and also frustrated that top defenses like TCU had figured out his offense. It seems he wanted the break from OC duties so he could regroup.
Still, there had to have been a better way to handle the situation, especially for the guy who was the only OC to make Heaps look good and now appears he will have been the only OC to make Mangum look good.