Diaz seemed to lack a certain snap to his punches. It didn't seem he "turned the punches over". He'd also sacrifice some power for volume. Given how often Diaz landed on Marquez, yeah a KO was a real possibility if he had good power. At the same time, Marquez may have been a little more cautious if Diaz had good power. And maybe Diaz wouldn't have landed as many shots. As said earlier, he seemed to sacrifice power for volume. So he'd throw less punches if he had power, and naturally land less. I mean Marquez had a long career, faced some good punchers, and how many guys were able to stop him?