You really can't use that one example as a guarantee of what's going to happen; for one thing, the circumstances at Chelsea are significantly different from those at United. There was stacks of evidence that what happened with Chelsea last season went beyond Mourinho (just think of Hazard's inexplicable loss of form, Ivanovic's complete loss of form, the shambles of a preseason, etc). A big mitigating factor for me though was what happened in the transfer market. If you look at Mourinho's record, he's usually very busy in the transfer window, but at Chelsea he didn't have the final say on transfers, and it showed. At united, he will have the final say. I think that's going to make a much bigger difference than you think.