At 135? Arguello was still a pretty awesome fighter, but wasn't quite as dominant at this weight as he was at 130lbs, or the latter portion of his career. Mancini troubled him, and Ganigan put him on the floor. Fernandez split a couple of fights with him too. I actually see this being a better fight than others. Diaz may not have a lot of power, but has a nice snappy jab, throws well to the body and head, and actually can employ some side-to-side movement every now and again. He takes a hell of a shot, so I don't see an early round blow-out. Diaz, I think, does quite well early, and it takes a while for the Explosive thin man to find his range with the jab. Once that happens, though, I think Arguello takes over, and gradually breaks Diaz down to score a late-rounds stoppage in a fight that up until the last two rounds remains pretty competitive.