That could very well be the case, Let's be honest, Pogba arguably our best player, world-cup winner etc doesn't seem like the best role-model for the younger players. The players that actually act the most professional are the younger academy lads, as you wrote, that says a lot.
A buddy of mine who is a Everton fan made a good point a few weeks back. How we looked so much more professional on the pitch when Ibrahimovic was here, not because of his qualities as a player but his professional approach to training, fitness and football in general. On top of that he is/was a strong personality and leader both on and off the pitch.
When it comes to James, I just believe he needs some rest, both physical and mental. We've used him as if he was a ready made superstar, he needs to be given time and patience.