How? Why? How come? This is what you're most likely now asking me.
Read and... agree with me, because thre would be nothing left to object.
So, lets first look at the competitors:
Nate Robinson. This 5'9" explosive little devil proved that he can dunk the ball (though sometimes it took him a dozen attempts). But... do you still believe that he can make it twice? Robinson, like Spud Webb in his era impressed the crowd with his dunks being such short in height. Now, when we all know that he can dunk we would expect something more than just dunk, we would want something like 360 windmill fro the free throw line (right, we've been spoilt with those unbelievable dunks by Carter, Jordan, Wilkins, Richardson, Mason and others, so now we want something really superior). With all due respect to Robinson, we all understand that doing something extraordinary cannot be done with his height (though... his between the legs off two feet dunk at the 2006 competition imressed me very much)
Conclusion: it's unlikely Robinson will defend his title. But my personal sympathy makes me wish him good luck.
Tyrus Thomas. While standing 6'9" he hasn't earned his name (and will he?) for his tremendeous dunks yet. Moreover, he's been already fined $10,000 for telling that he particvipates in the competition just for money (even if he doesn't win he'll get more than $16K). That means he won't be ripping his ass out to win in the contest. So my prediction is he'll make some windmills or off-the-board dunks or 360's (which are already quite standard for NBA players) and get his check. That's it. (By the way, who of you is able to recall some more or less memorable dunks done by Thomas this year?)
Conclusion: Thomas is not this year's contender, either.
We got Dwight Howard here. He's definitely a power dunker and power player (just look at him - he is a real basketball monster machine: 6'11" frame with 265 pounds of muscles). But this is not enough to win the contest. What is good in a game (power driving to the hopp and finishing strong) is not as good in the Slam Dunk competition. We expect high-flying, acrobatic, unusual dunks. I don't think Howard is as graceful as Kobe Bryany, as high flying as vince Carter and as acrobatic as Jason Richardson. Frankly, I don't think Howard will impress the crowd with his dunks (except for one thing: if he breaks the backboard. But I'm afraid it won't bring him a lot of points from judges).
Conclusion: the best achievement in the upcoming competition: runner-up.
So, after all being said above we look at the final man in our review: Gerald Green. 6'8" while just 2006 pounds, jumping high and sometimes quite creative in doing his dunks - he's the most probable winner of the competition. I don't think there are dunks he isn't able to do. All he needs at the competition is to be creative and show us something that we haven't seen (or rarely seen) at the previous contests. Moreover, I think both Kobe Bryant and Vince Carter (who are selected to be judjeg on the contest) will sympathize with Green: he's young about the same height as they are and jumps high, too. We all rememeber his dunks, especially that one where he dunked the ball after an off-the-board pass with his head at the rim level. I think, if Green tries, he can impress both the judges and crowd.
Conclusin: to disappointment of Nate robinson, Dwight Howard and Tyrus Thomas (well, i'm not sure there are) fans, Gerald Green is the new Slam Dunk champion even before the competition. Of course, it is less intriguing for the competition, but I'm sure it won't make it less interesting. We all love this contest (even though not everyone is ready to admit it)
PS Now watch some of Gerald Green's highlights: