Most entities within the game (fighters, managers, companies etc), will have a hype rating. This is basically their rank. We use "hype" because just like in real life, often the perceived quality of someone or something is different to the actual quality.
Fighter hype can be viewed as the fighter's ranking. Just as with real life, the fighter's perceived world ranking is not always a direct correlation with their actual skills. Similarly, your fighter's hype rating is dependent upon who they have beaten and what that fighter's hype was at the time.
If a fighter beats someone with a high hype rating, they will gain a lot more hype than if they beat someone with a low hype rating and a similar principle applies with losses and taking a hit to their current hype rating.
The higher the hype rating, the more people will want to watch them fight and the more people will buy Pay Per View's with that fighter involved.