So i was over at Pounding the Rock (spurs blog) and they had this FanPost about Defensive Stoppers in NBA. Obviously, most of the popular defenders were popped up and they used On/Off court defensive rating differentials to show where they stand. Well first of all I dont know how that Rating works up, and if some one can explain that I would appreciate it. Anyhow, this was the list provided by the fans there with the numbers (note: the more negative means the better the defender) :

Ariza: 0.239
Hill:1.022
Battier: -1.478
Artest: -4.656
Bell: N/A
Posey: 0.31
Jackson: 3.245
Wallace: -0.233
Deng: -2.927
Kobe: -3.563
Rondo: -1.081
Parker: -0.767 (Not bad!)
Manu: 0.832
Butler: -1.764
Jones: 0.761
Barnes: -1.185
Jefferson: -2.471 (wow!)
Lebron: -1.128
Bogans: 1.371
Udoka: -3.703 
Temple: -2.439 (limited minutes)
Chilai: -5 (definitely worth kneeling before)   (I am guessing this guy is just a commenter and its an inside joke?)

What the numbers (and again i dont know how that number was calculated) show is that Kobe is a really good defender (we already knew) and LeBron is no where close to be considered an elite defender.