Thats a big part of it. The other part is that Pride takes most of the other foreign fighters.

That's also why I think Sylvia is a much better HW champ than Arlovski. You can't hype the heavyweight division when your champion can't speak English very well. At least Sylvia can talk smack much better, and possibly bring a little bit of excitement outside the ring to the UFC HWs. God knows they need it.