Fedor proves that the best martial arts in the world is Sambo.
The Russians perfected this fighting style as they perfected most other weapons. Fedor is disciplined to the art and never waivers. That is why he wins. If you notice in his fights he conserves energy for select opportunities, depending on the fighter he is fighting. Other martial arts don't factor this. Similar to how gun manufacturers don't factor whether their weapons should fire after being dunked in water. The Russian's do factor this (Ak-47). Versatility is primary to strategy.