On top of the poor mentality of some players, I also question the fitness of some United players. When I watch Spurs, City and Liverpool every single one of their players puts in a shift both in attack and defence, and they're able to maintain their pressing off the ball and movement on the ball for the 90 minutes. If I was at United I'd be questioning why we aren't able to do that, whether some players simply can't be bothered or whether there's a lack of fitness there compared to the other big teams.
At this point I'm really not bothered if we lose the likes of Pogba, Martial and Lukaku in the summer, if they want to go and swan around the pitch for other big European teams then I'd be fine with that, I personally think they lack the physical and mental attributes required to succeed in the PL.