It seems pretty obvious that he's not as gifted as the likes of Martial and Sterling in terms of close control and being in complete control of the ball in tight situations. However, hopefully what we've seen this season is a bad representation of him in this regard, and even if he's not going to match the above two in the same, he can still do it to the acceptable level required at a club like United, and make the most of his other supposed strengths such as strength, invention, crossing and shooting.
If his season doesn't burst into life before the end of the season, we have an important decision on our hands, whether to put faith in him for next season, or send him out on loan to regain his mojo. Personally, I'd send him out on loan if LVG stays for next season, and give him a shot (in pre season till august) in case we hire a new manager whose system uses him better.