Man I get really tired of saying this over and over again, I should make it my sig or something. Upton just needs to work at his fundamentals on defense, it's nothing he can't fix over time.
No idea where you got the "serious attitude problem" from. Only thing close to that would be him arguing a 3rd strike call from an ump, where I believe he was right. If you want to look for a talented Rays prospect that has some attitude issues, look at Elijah Dukes...amazing talent but needs to get a hold of himself.