Manchester United has a bigger problem than just a few players, or even just manager, they have a management problem that is taking them longer to fix which is going to be very hard. I understand that if they change their manager then they could be a little better, but even if you get Pep Guardiola here, doesn't mean that they are going to win the league, or if you gave the entire city squad here and trade all united there, still they are not going to be the winners suddenly with the same manager and management.

This is why they will need many years, but eventually they will fix the squad, change the manager and have better management, only then they will do fine. Until then, they are going to just try to keep gradually and slowly become better.