Disagree. He failed because he had Josh Allen and tried to protect him and not let him be Josh Allen. If he goes to a team without Josh Allen, chances are he has to work with what he has - and I think he can be quite good. Its a risk for any team, but I'd consider taking a chance if I was looking for an OC.
He got a bit of a raw deal here. we needed to change to get a spark. He was the sacrificial lamb to some extent. Much more so than the actual root cause of the problem.