-- Ive heard a lot that he is a super high level disciplinarian/nut buster. When you are at the NFL level, if you do things that way, you HAVE to win, and win A LOT for players to buy in to that. He hasn't, so many locker rooms have turned on him or outright quit on him.
--Mangini accepted the Jets job unofficially during a Pats playoff run, and supposedly was recruiting players on the PATS to join his team in the offseason. Mangini was also the snitch in regards to spygate, and the whole thing going down. Given that Belichek was his mentor, I can see how he would be pretty sour with him after that stuff went down