One issue that comes up with Cyborg-Rousey is who should change weight - and tradition is often brought into it. In boxing the tradition is the lighter fighter goes up, and people are applying that to MMA. But in grappling the tradition is to stay in your weight. There have been several wrestlers and judoka who've won multiple Olympic gold medals (and world championship gold medals), and very few of them have gone up in weight. For instance, one of the all time great freestyle wrestlers, Satiev (google him, absolutely dominant), won 3 Olympic gold, 6 world championship gold, all at the same weight. No one in wrestling expected him to go up to the next weight division. It hasn't hurt his legacy in the slightest, there's no asterisk beside his name for not trying a heavier division in the next Olympics etc. Or take Rousey's own judo weight division. Ueno (twice Olympic gold, twice world championship gold, very dominant - better than Rousey both on the ground and on her feet), never changed weight. You can go through wrestling and judo multiple champions, and only find a handful who changed weight (Yoshida being one of the few). So for a grappler like Rousey, it makes more sense to follow grappling tradition than boxing tradition - especially since if you throw a pure boxer against a pure grappler into MMA, the grappler is going to win more often than not ... its a better pure tradition for MMA. And what's the UFC tradition for champs? Its very strongly to stay in your weight division until you're no longer champ. The only champ who, while champ, went up to fight a heavier current champ was Penn when he fought GSP at 170. That's it, in 20 years. Aldo never did it. Hughes never did it. GSP never did it. Jones never did it. Liddell never did it. Barao never did it. Anderson went up, but not to fight a champ (didn't fight Liddel, Machida or Jones, the LHW champs during his reign). Once you lose the UFC title, you might change weight divisions. Meaning, once Rousey loses her 135 title (it'll happen, it happens to everyone) she'd be following the UFC tradition to change weight (though as often going down as up). Going up in weight is mainly a boxing tradition, it doesn't translate at all to grappling, and not much to MMA either. If Rousey came from boxing it might apply to Rousey-Cyborg, but she comes from judo, and like wrestling, its very rarely done. Dominant champs are in the same weight divisions Olympics after Olympics, instead of going up in weight.