He is not the problem but his ego is. He has to realise he can't play every minute of every game anymore. We should be using him once every week or two in the right situation, where he can be lethal. Playing twice a week just leaves us with an empty shell that can't keep up with the game.
He also needs to stop drifting. He adds nothing when he's hanging out on the touchline. Stay in the box and do what he's best at.
I'm not saying he's gotta drift and go and do stuff that shouldn't be his role, but it will be just as much an issue if he stays in the box to be a static peon waiting for crosses that, unfortunately, are always pretty bad, save for an exception or two once in a bluemoon. The best version of him yesterday was the defensive and link up side of him... It should never be that the only thing I remember from a game of his are his defensive contributions. At the bare minimum, I should be remembering the chances he either missed or scored. Of course no team ever produces attacking goods every single game, but it's a recurring issue with United. As soon as United were all in and he was back to being in the box waiting for crosses, he vanished from the game as United vanished as a minimally decent attacking side. Once he saw it wasn't working out and when Cavani came, he drifted again and appeared more once again... And he wasn't wrong either, I cannot remember a chance from a cross in the last 10-12 minutes.
Edit: It's also an issue that he could be in the box or very close around it and players barely move up and cut through the central line of defense through quick, creative passing, we're barely able to do that too.
PS: this isn't a dig at his teammates, just general way I look at attacking dynamics this season