I also think the fact most people assume it's an easy win for Rousey means less sales. If I wanted to go an event I would avoid a headline like this as it could be over within 2 minutes and it doesn't have much name value in that sense.
The thing is though is that Carmouche is tough, Ronda won't be able to walk through her, it's just the way the media is portraying things. To refer back to an earlier post about blowouts, very very few people expected anything other than complete and utter domination of Bonnar by Silva, yet they all still bought. I guess in that regard, their names saved them though.