If you turned the clock back a year and asked MMA fans, who are the major stars in the sport right now, there's probably only really one name that would have been consistent out of their mouths. And even then, fans have never been all that happy to give Jon Jones much respect as one of the sport's top draws. Outside of Jones, there were a rabble of potential faces, some fading, some rising, some thrown out on the off chance that they may secretly become stars in the making. Two of those names were a point of constant debate among the hardcore fan community, Ronda Rousey and Conor McGregor.
For every fan willing to trumpet one of them as the next great star to draw the masses there were an equal (if not greater) number of jaded fans who remembered all too easily the "Machida Era," Cain Velasquez's massive Mexican fan base, and Anthony Pettis' face on a Wheaties box. It was an easy thing to sneer at McGregor and Rousey's potential popularity, as neither had ever proven much (if anything) as top draws to a PPV audience. Those days are over now.
For McGregor, many of the reasons are easy to see. He talks a great game, he walks a great game, and he's got a massive groundswell of home supporters willing to back him through hell and high water. As the UFC 189 World Media Tour unfolded, doubters that McGregor could pull in a large audience slowly faded away. By the time UFC 189 hit, even without Jose Aldo, most fans were hip to the idea that it would be a big drawing card and that most of the reason for that would be Conor McGregor. Not everyone, but most of them.
Ronda Rousey has been a bit of a different story, however. Reactions to her UFC 184 card, headlined by Rousey's title fight against Cat Zingano, grew increasingly pessimistic as the card fell apart around her, leaving Rousey practically alone at the top to carry it. And yet, the card shattered expectations with 590k buys. Finally, after months of chatter and debate, Rousey had proven herself as a major headlining star for the UFC... kinda... sorta... not really. Really the fight seemed more like a point where Rousey proved to hardcore fans that she was worth paying attention to. That she was good enough to be supported with the kind of general praise they might lob at Chris Weidman whenever his name comes up on a P4P list or booking announcement. It was a good enough showing to push away much of the remaining hostility some portion of longtime fans held toward WMMA's most dominant fighter.
But, if the lead up to UFC 190 was any indication, it wasn't enough to convince them that Rousey is a top draw. One of the reasons why, as Dave Meltzer points out in a recent edition of the wrestling observer, may be that unlike McGregor, or Anderson Silva, or Jon Jones, or any of the UFC's major stars before and around her, Rousey doesn't really need much MMA fan support to be successful. I think it certainly helps if MMA fans are excited for a Rousey fight. It energizes the media news cycle to put more stock in her opponent and more meaning in Rousey's narrative. Those are things that the larger mass market publications will pick up on (sometimes) and that kind of momentum could build something truly epic for her down the line.
But, ultimately that's a separate conversation: How would Rousey do with a real rival? Not whether or not she's a star headliner.
Rousey is MMA's biggest star, and she's become that, not because of massive fan support, but in spite of its scarcity. Rousey's role as the driving force behind WMMA in the UFC, along with her dominance in the cage parlayed her into a film career which, (h/t to Meltzer for pointing this out) now involves appearing in one of the top-5 highest grossing box office movies of all-time. She's got a best selling autobiography, landed spots in the Sports Illustrated Swimsuit Issue and the ESPN Body Issue, won ESPYs, and done it all largely with apathetic support of the entrenched MMA fanbase.
The result (and the reason, if you can take a little cyclical logic) is that Rousey brings in fans who otherwise wouldn't watch MMA, or even care about it. They don't read about it, they don't think about it, they don't know about it. But, they know who Ronda Rousey is and they show up for her. Of course, a large part of that audience is women, who the UFC has really never shown interest in courting as a part of their general message. But, and I'll let Meltzer say it, because I think he put it pretty deftly, "Whatever it was, and obviously it's a combination of a number of things, women related and even lived vicariously through a woman who took no shit from men, trashing ex-boyfriends in her autobiography, vocally coming out against their standards of what a good body is supposed to look like, and rubbing it in the face of a celebrity woman beater, as well as being the most dominant athlete in what is supposed to be and until a few years ago was a male exclusive sport in its top promotion."
And the thing about an audience like that is, they're not really going to care too much about who Ronda Rousey fights. They may toe dip in for one or two events before leaving the sport behind, they may be hardcore Rousey fans that eagerly await every event with her name on it, but it's a resource so otherwise untapped by the UFC's marketing efforts that she can probably bring enough new people to the table each time she fights that even if most of them only show up once she'd get a huge crowd every time. Right now Ronda Rousey is MMA's biggest star, and frankly it doesn't really matter if MMA fans believe it or not.