#2 Long term injuries to key players
It is true that in the Premier League, injuries to vital players can halt a club’s aspirations of winning the title (look at Arsenal, they are the masters of this art). But then, that is why you need to have a strong bench.
Right at the start of the season, Mourinho was adamant that he would have a squad featuring only 23 players. He had deemed that those 23 players were enough to achieve the objectives of the season. Later on, he had to eat his own words.
Injuries had left United threadbare in defence. Mourinho tried all possible permutations and combinations in defence. Luke Shaw, Marcos Rojo, Phil Jones, Chris Smalling – all spent major chunks of the season recovering from injuries.
In midfield as well, the situation was no better with Michael Carrick having to start more games than was initially planned. And, if Juan Mata’s injury left United without a creator, Ibrahimovic’s ligament tear left them without a finisher.