The theory is when they changed the rules about walking to halfcourt or whatever it messed up his routine. Which kind of makes sense, cause he is mental.
I kind of think he bulked up to much, after the MVP season to preserve his body and screwed up his shot, even more. He usually enters the season with Alonzo Mourning looking shoulders. I think that's why he plays better on the back half of the season too, he sheds some of the muscle the first couple months. It makes no sense that someone looks more explosive the second half of the season. I keep waiting for him to go full David Boston.