People talk way too much smach about Rockholds chin, the guys has just eaten too many bombs, before that he had a good one, his problem was always his defence.
He took some bombs from Jacare and he wasn't out after taking that spinning heel kick by freaking TRT-Rex Vitor, he needed additional ground and pound to stop him.
He never had great defence and after the Vitor fight and probably a lot of hard sparring (AKA seems to be really old school) his chin was no longer the same.
Prime vs. prime I'd give the advantage over Wanderlei, but grappling was never Wanderlei's big weakness, usually he lost when he was outgunned in the striking department/the other guy could take his big shots but he couldn't.