Norv Turner is proof of the Peter Principle. You keep getting promoted until you reach a position at which you will fail. In most cases you get one shot at failing, but somehow he has gotten three.
The other crazy thing about the hire is that I believe AJ Smith had both coordinators installed before he hired Turner. In fact because Marty wanted one of his relatives considered is the biggest reason they fired him. Instead, AJ went for that “proven winner” Ted Cottrell. Most coaches hire their assistants (can you imagine a GM telling Parcells who to hire), but AJ Smith has such a big ego he did it all himself.