It looks like he did the right thing and trained the crap out of his legs, but to be honest, not a lot of difference between his 2 pics, and he gained less than 20lb in 6 months. If he'd eaten more, backed off on the cardio and lifted heavy he could have put on much more size.
Currently training for raw competition.
Gym PR's at 242-
465, 345, 515, 1325