The problem for her is that 90% of her wins are against women who can fight at 135 or even 125 - that's simply not impressive. Its not Cyborg's fault that there are almost no good WMMA fighters at 145, but its also not a 135 pound fighters responsibility to go up in weight to fight Cyborg. Beating Nunes will do little for her legacy, because she'll be beating just one more woman who's smaller than her - she needs to beat good 145 WMMA fighters, not smaller women, for people to take notice. People expect the bigger fighter to win, there's little legacy in doing so.
The one thing Rousey did much better than Cyborg was market herself. Rousey had a bronze medal (for a country that gets 100 medals every Olympics, most of them gold and silver) in a sport almost no one in America watches (seriously, almost no one in America can name a single other judoka besides Rousey), and made herself into a such a big household name that the UFC decided to make a division for her. People wanted to see Rousey, and women wanted to fight her, because of Rousey's marketing.
Cyborg, with a much better resume (WMMA wins) put almost no effort into marketing herself; she seems to feel it's beneath herself to do so. That's her right, but then its silly for her to complain that she's not popular - MMA is largely self-marketing, and you can't expect others to do for you what you can't be bothered to do for yourself.
She should be studying Rousey's marketing techniques - Cyborg would be starting at a very advantageous position compared to where Rousey started marketing from, she could become as big or bigger, if she put in the effort.
