The main problem with United, I think, it's that the players they rate highly (the club, the coaching staff, and the fans as well) are really not that great. Many of their first teamers are average players. If you follow the Martial thread on Redcafe, you'd think he's some sort of French version of Neymar, that's how highly they think of him. In reality, Williams from Bilbao is very close to Martial. Just an example.
Another example is Schneiderlin. Great player according to many United fans, yet, at 26, his European experience is almost zero. Zilch. Non-existent. Is that, really, a great player? How?
EPL is like a bubble where standards are created by the system and they exist only within the system. Average players are called great, and good players are considered incredible, or world class. There are maybe 5-6 world class players in the entire league. United has (arguably) one, De Gea. And his form is nothing special right now, I think Claudio Bravo is better at the minute.
United is the best example of a distorted Premier League type of rating players.
A film like Moneyball (with Brad Pitt, just watched it again yesterday, great movie) could be made based on the british style of evaluating professional football players.
Actually, what happens at Leicester FC reminds me of Moneyball, players that nobody rated, nobody even knew they existed (let alone had interest in buying), have taken the no1 spot in that League just by following basic football principles. It's a clear example something is way off in England. Way off.