You see, it’s all too simplistic to look at it the way some have, without taking into account the type of football and tactics. For example, De Gea is an utterly incredible goalkeeper. He was worth a number of league places by himself. Any team, including Liverpool would be blessed to have him. Would I pick him ahead of Alisson in a world XI... yes. Would I pick him ahead of Alisson for Klopp’s Liverpool... no. Alisson is crazy-good with his feet (without even judging his time at Liverpool), and suits what he’s trying to do. In honesty, there’s very few players I’d want from United to go into a Liverpool team. I certainly wouldn’t want Lukaku, Valencia, Bailly, and the idea of Smalling... oy vey.
Now, if you’re fitting players into a Mourinho team, essentially going the other way, there’s loads of our players I wouldn’t pick ahead of Lukaku, Smalling, et al. It’s not just about who the best players are it’s about who the right players are. As for the criminal underrating of Milner... the less said the better.