He's a great young player, with potential to improve. It could go either way for him, Utd could make more good signings and with a lot of luck the team could gel with the lad performing well. However, Utd could continue their deteoriation with the lads form and confidence taking a hit. He may fall within both this season, good start that tail off as the season progresses.
If he does struggle though I don't think it will be due to his ability. His difficulties may be due to working under an average manner, poor recruitment and a fan base with delusions of grandeur of manic proportions.
This lad is very good though and under the right coach would improve.