UFC 121's headliner between Cain Velasquez and Brock Lesnar gets some high powered attention from CBS Sports National Columnist Gregg Doyel and he makes an interesting point:

UFC heavyweight champion Brock Lesnar lost Saturday night, and this is why mixed martial arts is the greatest combat sport in the world.
See, Lesnar should never lose. He's bigger, stronger, faster, meaner than anyone he will ever fight. Lesnar's a freak of nature, and if this were boxing, his record would be something like 41-2 -- which is the record of WBC heavyweight boxing champion Vitali Klitschko.
In boxing, the very best fighters don't lose. Not ever. Floyd Mayweather is 41-0. Klitschko is 41-2. That makes for great legacies but predictable fights, because when Mayweather fights, he wins. Plunk down $45 for that pay-per-view, but only if you like to watch a story whose ending you already know.
Me, I'll stick with MMA, which is beautiful because you just don't know.
This is why Dana White and Lorenzo Fertitta are the big winners in the long run from the outcome of UFC 121. Yeah I commented on the short term money they'll lose because Brock isn't the champ anymore, but in the long run this is a huge win for the UFC and the sport. MMA Payout has more:
The business implications of this fight are several and involve a bit of a trade-off between the short and long term. Lesnar is the sport's top draw and best mainstream enabler, but he's likely to lose a bit of his appeal without the belt. Certainly the 1 million buy guarantee is probably gone unless he fights Mir in a rubber match or lands another title shot. However, it is my belief that we've witnessed the birth of the next big draw in the UFC in the form of Velasquez. He may not be the most stirring interview or imposing physical specimen, but he finishes fights and that is ultimately what the fans care about most.
Velasquez also happens to bring a new demographic to the table. Say what you want about the UFC's marketing tactics for this fight, but it knew it had to hedge its bets when promoting this fight. Velasquez may not sell 1 million PPV buys every fight, but he will prove to be a solid draw for the company on the merit of his 89% stoppage rate and the fact that he gives them a somewhat credible entry point into the Hispanic market both North and South of the border.
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The Lesnar loss probably isn't optimal from a short term perspective, but the combination of Velasquez as a dominant champion and Lesnar as versatile non-title draw will help the UFC cover the gap and even come out ahead in the long term.
This was actually crucial for the UFC because, as our own Jonathan Snowden pointed out before the fight, had Brock Lesnar kept winning, he threatened to emerge as the first UFC fighter since Royce Gracie to become bigger than the promotion.
Eventually the UFC will produce a true superstar who transcends the sport and the promotion, but that won't be happening in 2010.