Rafael Tobias

"Bipolar". That's what they call Rafael Tobias, and is part of the UFC light heavyweight division's deep end, fighting out of Brazil — 16 pro fights in, still swinging for a number next to his name.

The game is built on grappling: 4 takedowns per 15 minutes, and opponents spend rounds defending instead of fighting. 6 submission wins say what happens when the defense slips.

He's coming off a loss to Diyar Nurgozhay. Careers aren't defined by the fall, though; they're defined by the rebound.

And here's the scary part: he's 23. 16 pro fights before most fighters hit their prime — the ceiling is nowhere in sight.