#3 Play a higher line/press from the back
This idea needs no justification, really. Mauricio Pochettino's Tottenham Hotspur and Antonio Conte's Chelsea have benefited so much this season in the way they press teams as soon as they lose possession. Even the centre-backs are mobile enough to push up to the half-way line and help the midfield out with regaining possession.
For Manchester United, they have Eric Bailly, Chris Smalling, Phil Jones and Marcos Rojo who could make the most of the situation with aplomb. They're all fast, excellent readers of the game and have the kind of physical presence to win the ball back, contributing to the midfield.
With only an average of 13.1 fouls per game, the side is depending too much on individuals to get them out of trouble rather than fusing the attacking instinct and ruthlessness of the midfield as well as the legs and the intelligence of the defence.