Diego needs to go back up to 170. Besides fighting Nate Diaz, who else can he possibly beat at 155? Not Guida, not Florian, not Sherk, not Griffin, and not Penn. Diego can fight Frankie Edgar. How about that for a money fight?
At 170, Diego has the speed advantage over guys, had the aggression (depending on which version of Diego goes into the fight) and had the power. Last night, Diego kept hitting Stevenson over and over with power shots and uppercuts. Stevenson looked like he was getting hit with pillows.
Diego lost all his power dropping down to 155, didn't have that much of a speed advantage over Stevenson and will still have the same problems with wrestlers, especially at this weight division. At least at 170, he can knock people out. And considering he has literally become a boxer, thats a good thing.