Maybe the problem with Stewart?

If any of you guys follow MMA, you see that some guys who are fairly young start to diminish competitively (Fedor, Rua). It has nothing to with age, but the mileage on their body. They've been in worse battles than most and it takes it's toll.

Stewart has been one of the fastest guys but has always crashed the most, and that has to have an impact. He has taken bigger hits than almost any rider I can think of, and he gets back up and keeps on going. At some point, it will have an effect and maybe he has reached that point. If you look at Sidney Crosby, he hasn't been able to play for the better part of 2 years because of hits to the head. Without any scientific evidence to back it up, I would argue that many of Stewart's crashes resulted in harder hits to the head.

I may be off base, but it's definitely something to keep an eye on now that the damage of head injuries is more known.