It's not just viability for viability's sake, although I'm not exactly in disagreement with that option. It's compared to other fighters. I don't think he's underrated generally, I feel he's underrated compared to the top tier. In MMA, there are only a few fighters that truly are miles above their competition and even then it's usually only in a few areas. That's not really reflected in game for the most part when it comes to the lower tier.
I do agree that every change you make is substantial. It's just that those changes still have them far below the top tier. So the solution to make me happy (which might not be someone else's) would be to make the gulf smaller by bringing the numbers up or to lower the impact points have overall. Both could be considered inflation in a way, but that's no necessarily a bad thing. Stats shouldn't mean that much in the long run, just enough to highlight the strengths and weaknesses of fighters. Whereas right now, even with the scale for important stats really only being ~84 to ~97, the difference between that 84 and 97 is too steep. In my opinion.