I agree that players at that level have a strong propensity for "cockiness". That wasn't TMG's problem in HS. His problem was insubordination, insane lack of defensive effort, and a total lack of respect for his teammates.I'm not sure that's completely fair.
A lot of guys are different when they hit the reality of not being way better than everyone else in college. If you look at Newell, I thought he looked pretty cocky in high school, but he seems to have accepted his role and actively worked to improve as a player and teammate.
Granted, Cal isn't as good as TMG was as a freshman, but I don't think on-court attitude is a great way to judge character.