In an old-style tournament format, I would tend to bet more heavily on people that are good at avoiding damage.
Would Fedor beat Silva? Probably. But after two fights, I think Silva would be in much better condition. Fedor tends to take a lot of damage, and Silva almost never gets hurt.
Fedor is statistically the least hit fighter in MMA. He also has more 100% accuracy fights than Silva. And we all know Fedor's cardio is endless.