Serious question: Why is it that wrestlers generally peak in their early to mid 20's and start slowing down by the time they hit 30 (with some notable exceptions, for sure), whereas MMA fighters seem to be in their prime until mid-30's or later? (Compare Anderson Silva and Khajimurad Gatsalov, arguably the best guy in each weight in the current era).

I'd imagine that less frequent competitions in MMA have something to do with it, and arguably PED's as well. Thoughts?