Diego beat up Karo. That's tough to do.
And he doesn't seem to lose energy. He finishes matches at an energy level like it's the first round.
Eeven if you suck, but you can get past two rounds and your higher skilled opponent is winded, you will own him if you can push him with your superior cardio.
When you're trying to fill your lungs with air and your opponent is coming 110 MPH, you are deep water with no paddle.
I think that's Diego's greatest asset. Coupled with very good skills, heart, dedication, faith, and a strong will to win, he's going to be hard to beat.
Some guys may have more skill now, like possibly Hughes. St, Pierre, and Penn, but Diego looks like he wants it. He'll make for some interesting match ups.