#3 Tweaking the formation

The main issue that Man United now faces is a lack of shape to the team when they go out on the pitch. The right flank is left empty at most of the time leaving a huge gap in the attack. Players like Lingard and Mata tends to move more central leaving a whole portion of the field vulnerable.
Mourinho is a manager who would like a 4-3-3 holding midfield formation. So his ideal midfield would be Pogba and Fred with Matic holding down the fort. Sanchez has occupied the left wing with Lukaku up front. So players like Rashford and Martial should play at the right wing rather than Mata and Lingard simply because of their pace and the width they could bring to United's game.
A rather unusual choice to change their formation is to try the 4-4-2. During the first four games we saw teams like Watford and Arsenal using the 4-4-2 formation with Watford using a classical wide 4-4-2 while at Arsenal we saw something which was more central like a 4-2-2-2. But in any case United could try changing to that with Pogba and Matic(or Fred) at central midfield, Rashford and Martial at the wings and Sanchez and Lukaku staying up front.