Dallas head coach is the former offensive coordinatorDallas had a head coaching change. When he went to the Cowboys, they were shit on special teams and almost immediately he improved them to top-10 status, where they remained throughout his tenure there.
The only thing I know about him being a thorn in McVay's side was the fake punt issue. I don't think characterizing him as a rotten apple is fair, particularly when he did an excellent job with the Cowboys. I think his departure there was more the new HC wanting his own guy, which happens frequently even when the guy being replaced is good.
And he opted for a "fresh start"
Its history repeating.
Rams won a SB without him because culture matters.