The Keys to Success for Tommy are Health and Head. I'm still not completely sold on his head. He's got to prove that he can stay focused throughout a match deep into a huge tournament. I didn't see that happen in Miami. After spanking Ferrer in the 1st set of their SF match, he effing went off the rails again. It's one thing to lose a set, it's another thing to lose your focus and not be able to regroup for 20 minutes. He pulled it together at the start of the 3rd set, but the mental seal had broken by then. It was easy for Ferrer to take control of the match. Tommy can give away sets to the likes of John Isner in a 3R match, but not to the likes of David Ferrer in the semis of a big tournament, and there's a huge drop off from the Top 4 to Ferrer.
Love Tommy, his variety, and as Luggernaut said, joy for the game. But he reminds me so much of my other favorite, old-Marat. Too many self-inflicted wounds.