I outlined in my post that the reason was attitude and not talent. This is something Jose hammered on too. He too highlighted that it was Rashford's attitude that kept him playing and always in the squad even through his drought. That's the thing. A young player can blow hot and cold and be inconsistent. It's the attitude that counts though. Januzaj had the same issue - attitude. Same for Ravel long before. At this level, to my mind at least, it's the attitude that separates the good from the great and if he continues to let his head drop and allow his personal life to affect him to such an extent, maybe we should be more pragmatic than idealistic.
Rooney - barely a squad player; Januzaj - gone before the season started; Depay - barely involved and then sent out at the first opportunity. So in effect, we lost only Ibra and have brought in Lukaku. Martial was so far down the order last season that if we add a proper winger, it's in everyone's (including the club's) best interests to allow Martial to get first-team games on a loan.