Well, from the outside looking in there doesn't seem to be any other obvious reason why he would want to transfer. He just won freshman of the year in the best conference in college basketball, went to the sweet 16 and had a star making performance along the way. So of the main reasons a player would transfer:
1. Playing time/role
2. National exposure
3. Relationships with coaches/teammates
The only possible explanations are relationships and money, and no one has reported him having problems with anyone on the staff or team, so that just leaves money.
We don't know any of those really - especially #3. It's all speculation, but that's what twitter and message boards are good at, right?