1. Mental weakness
The Manchester United squad has been accused of being weak mentally. There is seemingly a lack of desire to win, as evidenced from the fact that several United players were jogging half-heartedly on the pitch during the 4-0 drubbing at the hands of Everton.
When United were playing beautiful, incisive football, the players were happy and effective. However, when faced with tougher challenges, the red half of Manchester has been unable to buckle down and grind out results, even if they are not playing at their best.
Additionally, Alexis Sanchez's incredibly high wages have caused other members of the team to rethink their own options and wages. David de Gea reportedly wants to be paid on par with Sanchez. The club is unwilling to do so and, as a result, De Gea may seek a move away from United in the summer.
Manchester United are a huge club with an amazing history. They do, however, have a lot of issues they need to fix before they can challenge for the title and Champions League again.
Some will be solved easily, such as the buying of a world-class centre-back. Some challenges, such as Solskjaer instilling a winning mentality and stronger backbone, will be more difficult.
Manchester United will likely be a force to reckon with next season, but this year, the club will remain out of the top four and will play in the Europa League next year.