Since Sir Alex Ferguson retired as Manchester United head coach, Manchester United has been struggling in the Premier League, and the coaches that have coached Manchester United since Sir Alex Ferguson retired couldn't solve Manchester United's problems, so I think the Manchester United board and the owner are responsible for Manchester United's problems. Manchester United needs to change ownership before Manchester United fans can see the change they have been looking for in a long time.
Sir Alex Ferguson can use normal and average players in his squad very well and even can build up a winning team with such players. Manchester United had players like Fletcher who was not sort of talented enough to be a star player but he contributed considerably for Manchester United under excellent management of Sir Alex Ferguson.
With other coaches after Sir Alex Ferguson era, no similar quality of their management was seen so far. The only coach who came nearly to this is Jose Mourinho but unfortunately Manchester United did not put all of their belief and strong support for Jose Mourinho, but they put it to Paul Pogba. It was their terrible decision and mistake that costs them many chaotic years later.