I've seen him beat his fullback almost every game only to not be able to hit the target or find his teammates.
His awareness is arguably his biggest weakness. He doesn't need to play centrally to develop it when it's also what's holding him back on the wing. Let him develop his awareness on the wing, where everything is in your field of vision. Let's worry about later, later.
I just find the notion of him playing out wide hampering his development laughable. Even it were true (which it's not), Man utd first XI isn't a learning school. The wing is his best position currently and it isn't the reason why he's not scoring.