Last point - at the professional level it is MUCH more likely for a player to significantly develop or "improve" mentally than it is for a player to significantly alter his physical ability or skill set.
That's why I don't like to bring the locker-room chemistry part of it into the game.
I don't get that. A player is the best player on their Biddy team. Then they go to Modified Basketball and find out that being the best scorer on the VFW team doesn't mean much. Sometimes that kid learns to be a team guy and a better player, sometimes he doesn't.
Best guy on a highschool team goes to college and finds out that scoring 28ppg for a class C school in po-dunk NY doesn't mean much at St. Bonaventure, and he either learns to be a better team player and adapt or he doesn't.
Best guy at Texas A&M finds out that everyone in the NBA has his athleticism and skillset at the 2 guard position, and he either embraces being a role player, or he doesn't, and goes to play in Europe.
Allen Iverson finds out that he's not a starting caliber guard anymore, and would rather go play in Turkey than come off the bench in the NBA. And he's not some cocky 25 yr old, he's freakin 34!
Yes, there's a chance that he'll be alright, but there is also a larger chance that there will be some friction.