Were you thinking of Diaz as maybe a poor mans Chavez? That's kind of the first thing that popped in to my head. But then I think that Diaz doesn't have all those subtle skills Chavez had and used so well against Rosario. I'll take Rosario by stoppage too.
oh no. I never for an instant mistook a great like Chavez for Diaz or thought about him. Diaz is good but Chavez was amazing.
Rosario, brutally. Chapo was an excellent counterpuncher, with alot more power than Marquez. Diaz would rendered unconsious within 5 rounds.
About the only thing going in Diaz' favor is that Rosario didn't seem to quite know how to deal with Chavez when Chavez crowded him. Pushing Rosario back and staying in close made him much less dangerous. However, given the murderous power of Rosario, the defensive lapses of Diaz, (and his inability to adapt to them, like how he never did anything about Marquez' uppercuts) and the inability of Diaz to inflict punishment, I don't see any way that Chapo doesn't KO him.