#2 Mourinho doesn't have the right players to implement his philosophy

Mourinho's teams are always built on a strong defensive base, pacy wingers, and strong forwards. In his first title win at Chelsea, Mourinho had the right players like John Terry, William Gallas, Claude Makelele, Arjen Robben and Didier Drogba to implement his philosophy. It worked wonders for him in Porto and Inter Milan as well.
But at Manchester United, Mourinho could not get the right set of players to play his style of football. Romelu Lukaku struggled on multiple occasions against stronger opponents and the back line looked vulnerable. Nemanja Matic gave him some defensive stability but the wing play is not world class.
Mourinho frequently modified his formations and used an ultra-cautious approach when playing against the top teams. As we have witnessed this year, United sat back and defend the whole game, when they played Liverpool, Arsenal, Chelsea, Manchester City, and Tottenham Hotspur. Mourinho's bizarre tactics have let United down quite a few time this year.