Firstly I will state I am an Arsenal fan for my sins.
But I think that everyone knows how and what Mourinhio does, and I never thought he was suited to Man Utd or at least the Man Utd I have seen in the last 20 years, for the similar reasons he did not suit Real Madrid even if he was partly successful there.
He wants to create a them vs us underdog backs to the wall mentality, he always needs an enemy and respects nothing or nobody, I don't feel that he loves football, or sees any beauty in the game, he is pure pragmatic, for these reasons I think he can't succeed ant Man Utd, as your history is to play attacking football. I don't think he cares about how entertaining the play is he only cares about trophies and his own ego, and if looks like the trophies are not coming then he starts attacking everything around him, the suits at the club, the players, the media, the owner, the medical staff, the fans, the history of the club until he gets sacked. I think he is at the stage he wants to get sacked.
He does better at a small club or one that has no style/history like chelsea or are really desperate for a trophy they "sell out" to clown antics for a trophy. It used to at least have the payout of a title, but I think now he has been left behind, the english clubs have so many game changers even at the smaller clubs, it is hard to win 1-0, 2-0 and he does not know how to change. I think your club should get shot of him and get somebody in that is more aligned with the clubs stature/history. somebody forward thinking with an attacking style.
I think he burns out attacking players, telling them they don't track back enough, then tell them they don't create enough.
I don't think any of the managerial choices after Fergie have been a correct match, but then how many great attacking coaches are there to get at the moment.