Yeah saw that video awhile ago. GSP is a beast to say the least. He can front squat about 260lbs.
Evans isn't very tall for his weight class, true, but he has some seriously thick legs which is where most of his muscle mass takes place. He has a smallish upper body but his lower half sort of justifies his weight class. And remember he walks around at 220lbs and has fought at Heavyweight before. He isn't as small as he might appear.
Why Do We Fall?