Since you are new, you have some catching up to do...
1st, BJ Penn is a great fighter, probably the best 155 lb fighter, but he got smashed by GSP when he moved up in weight. Also, excellent work ethics? BJ's problem and biggest question has always been his work ethics, the guy lost some fights because he was out of shape.
2nd, how is Machida relentless? I've seen a lot of Machida fights, even ones outside of the UFC, and he has never been relentless. The guy has a great gameplan, which is hit and run. But the last time I saw Machida fight, he was getting beat by Shogun (my 2ne fav. fighter). So that part of your observation is wrong aswell.