Hmm...interesting fight. Both had power, both had somewhat leaky defences. Rocky was as tough and tenacious a fighter as there has ever been. Jackson was probably better schooled as a fighter, but technically he wasn't great. I think Rocky would be the one forcing the action, making Jackson give ground as he (Jackson) tries to box him. Jackson I think would struggle to cope with Graziano's roughhouse, brawling style and would not have the adaptability to turn things around. He would slowly get beaten up I feel. So I tentatively pick Graziano by stoppage in six or seven rounds. However, if Jackson hits him with one of those sick punches he could throw, the fight would be over. Jackson had genuinely frightening power and with a guy like that anything can happen. Still, I think Graziano's pressure would ultimately be Jackson's downfall.
I think Jackson is the more well-rounded fighter and probably even hits harder (as most of Graziano's big KOs seemed to come against welterweights). I'd take Jackson by KO within about 5 or 6 rounds.
Both did indeed have great power I have collected a ton of lists over time (you know, AP, Ring, boxing historians,...) and I looked up who was ranked where to my surprise Graziano was ranked higher every time. So the way I see it, it comes down to defense (just kidding, what defense?) stamina and ability to take the pumishment these two would be dishing out for Jackson to pull ahead. I'll go with Graziano by the slimest of margins by KO-but I don't bet on it.
I'd say Graziano had the better chin, and that's what gets him the win in a slugfest. Graziano's chin, while better IMO, of course wasn't granite, and the reverse could always happen.
Jackson flattens him within 3 rounds. Rocky`s non-existant defense doesn`t bode well for him, and Jackson with his shorter, straighter punches would land first and often and take him out.