#4 Squad restructuring
It's popularly said that Mourinho wasn’t given the best of the squads to work with. It was an odd mixture of signings from eras of three different managers. There was a lot of deadwood too, with the squad being bereft of any identity. And one could easily put it down to frequent change of managers.
But Mourinho was at the helm of a significant restructuring. He got rid of a lot of deadwood, and signed a number of young players who will be a part of the club’s future success. Lindelöf has the attributes to be a good ball playing centre back. In Diogo Dalot and Shaw, the club have secured the full back position for at least 10 years.
While Bailly is currently a little unpolished, he is young and can develop into a good defender, as he has shown many times. Lukaku, at 25, still has plenty of time to develop into a much more lethal forward. Fred and Pogba can command the midfield for years to come and Joel Pereira could one day take over from the mighty David de Gea.
It's not far fetched to say that Mourinho left the club with a solid foundation for the future.