>Sure is a good No True Scotsman you've got there. And I'm not even sure you'd be right ignoring that; recall that sports like boxing and MMA separate people into weight classes that are ten pounds wide. In other words, those sports think that, within the bounds of "professional", there is no amount of innate ability or training that can balance out a 25-pound difference in weight.

That's actually a bad example. UFC got its start with the spectacle of watching comparatively small Royce Gracie beat fighters with significant weight advantages who didn't know how to grapple.

There were some really extreme weight mismatches in 90s MMA: http://www.espn.com/extra/mma/news/story?id=3513974