Funny I never see GGG have problems cutting off the ring and I'm not sold on him yet. When less talented fighters like Donaire and Pac can't cut off the ring, their opponents are called runners. If you have skill, you are the general of the ring.
To be fair it's a lot easier to cut off Stevens than it is Rigodeaux... Rigo uses a lot of tricks to get out of close spots and turn the person the other way...(hooks that he spins off of or a leftpower hand that he can also spin off of)
You're falsely assuming that Rigo and Bradley are a bunch of tomato cans and don't try to out think opponents. They're both undefeated and rated top 10 p4p for a reason. Even then, Pacquiao beat Bradley and won convincingly.