He was promised that he could run his offense with no interference and that promise (along with the pay) resulted in him taking a pay cut and basically making a lateral move from a job standpoint. But he was not allowed to run the offense he wanted, and instead was forced to run some mix of what Pruitt wanted and what Will Friend wanted. When the offense struggled as a result of 1) the mixed messages and 2) operating a power running system without the personnel for it, Pruitt attacked him for it instead of backing off and allowing him to run his offense.
He was then pulled from the booth - where he preferred to coach - so that Pruitt could more closely watch him and “keep an eye on him” and the plays he was calling. Again, that’s not how you treat another adult/peer you hired to do a job.
The public tongue lashings were the last straw. He was embarrassed - as any of us would be - and didn’t like being the scapegoat.
He was going to do whatever it took to get out of here after the season. It just so happens he fell forward into a head coaching job.