It's not about draft position IF all the talk before the season even started about him almost certainly being gone were true. IF that talk was true, it's simply a guy that is done with college, and knows at worst he can make a good living playing overseas. Nobody before the season had him projected to go high enough to warrant him leaving, if that were his reason.
I think he's just done with school. Wants out. Which is odd, b/c Buddy really seemed to me like the kind of kid that would be more likely to come back and finish his 4th year, than to leave early for anything but a top 10 type guarantee. College seems to "fit" him.