His lack of acceleration and stamina hinders him in one aspect (doesn't find space, struggling to avoid his marker), the lack of solid passing and first touch hinders him from another aspect (can't set himself up, find his team-mates or dribble into space).
His finishing I have no doubt is still up there but with all those hinderances he's not going to get chances against decent sides.
I think we are watching the end of his United career. RVP was much better than this last year and Van Gaal got rid of him.