Reality is, there are some things about motivation that are involuntary and subconscious. For all of us.
When we ran track, occasionally we would run 200's in practice and our coach would get us to really treat them like the real deal, but we'd always run them faster if we had someone the same speed next to us than if we ran next to someone clearly slower or faster.
AM had no real competition and he had a lot of 'savior praise' from his coach, the media, and the fans his sophomore year. Optimism was sky high, we ended his freshman year on a huge momentum run, and the hype and mood were unbelievably positive.
Even if he's the most mentally determined player on the team, that will still have some kind of involuntary effect on your drive. That's not really an excuse, but rather an argument that we shouldn't (yet, at least) be overly worried about this imo.