What's weird about Exum is that when teams did their psych/personality tests on him, there were reports that he came out in the elite percentile as far as mental toughness/competitiveness. Scores that reminded them of a Kobe personality. Now he plays so timid. The jump to the NBA from Aussie kid ball has obviously been as steep of a learning curve as there could be. I think that killer instinct is still inside Exum, but his transition to the NBA has been a shell shock for him, so we're not seeing it right now.
Hopefully he buffs up this summer (I think his frail body makes him scared to take a hit and risk injury, thus he doesn't even try to score when driving), develops more skills, and let's the game come to him. A year in the NBA should help him calm down, show him what he needs to work on to then come back next season and stop playing like a scared ****.
I'll reserve judgement on him for now, but if he doesn't show dramatic improvement by this time next year, we've really got something to worry about. He's definitely got the most to prove out of anyone on the team. But I have faith in him.
Where did you read that? The only such story I remember is from the Bucks psychologist, who said they passed on Exum because they wanted someone with more mental toughness and determination.