I have to very close friends that are associated with the sports departments in Division I schools. Ones a SID at an ACC school and one is an AAD at a Big 10 school. Both told me horror stories about Giddens behind the scenes that never get reported that confirm what Donny has said. He was, at least in college, almost right up to the end, very immature. And believe me, some of the stories I've heard, confirm it.
Oh yeah, I absolutely believe that he is incredibly immature. Just watching him in warmups, he looks like a hyperactive little kid, who just wants to have fun.
This does not mean he can't be a good player, because at the same time, it looks like he genuinely loves the game, and has tremendous energy...he just seems to lack the focus that you see in other guys (like Walker, for example).
But honestly, I don't think that is why he isn't playing (Tony Allen was playing, wasn't he? And he has a very similar personality). I think the reason he isn't playing is because he is behind the curve on the court. Which is not really that strange in the C's system, and as Leon Powe has proven, it does not mean that he will not catch up to the curve eventually.