well, I think he looks great in that movie, but, it's funny how in Fight Club Ed Norton looks like crap..but, a few years before he too looked great in American Hist. X
When you look at pics of Brad, he looks like an average skinny guy. He likely doesn't train at all for months , then a movie comes up.. he rents nutritionists, strength trainers, plyometric instructors..etc. he does nothing but sleep, eat and train for 3 months prior to shooting..and Wham! he looks great cuz his porportions come out as he looses fat. He likely does super high rep, lotsa cardio and eats dead on. Norton did the same thing in Amercan X.
It's for film, so, you don't have to be big..you have to appear big. if you are really lean and cut, you will look big. but, put your shirt on and you will look small. Vice versa for guys who are not lean