The thing with sabermetrics is that the stats that it's based off of have hundreds or thousands of repetition of the same events.
Yes some fighters fight a similar style, but not nearly like pitching and hitting in baseball. They also have one fight every few months, whereas sabermetrics needs way more detail to predict properly (hence baseball being perfect for it).
Stats tell you something in mma. It's just that you'd need to be factoring in everything in the gym to even begin to have a better idea