Are you saying that Mancini was the type to run shamelessly from his opponent round after round, clowning all the while?
Basically. Arguello was a slow starter, and he wasn't very quick. Mancini had good handspeed, and was a fast starter with a lot of physical strength. That's why he gave Arguello a tough fight early on. Against Duran, Mancini has no edge in quickness or strength. And skill wise, Ray's not in the same Universe.
Mancini can be counted on to give nothing but 100% effort in this. He would do everything he could to try and win, but Duran is too good defensively, his timing too sharp, too consistent. It would be different than the Arguello fight where Arguello's measured approach meant instead of landing 9 or 10 good shots per round, he landed 3 or 4 GREAT shots per round. Duran would be doing the 9 or 10 business, especially with catching Mancini with clean body shots under the looping shots of Mancini... eventually, while Mancini's will remains staunch, his body breaks down and he is stopped late with Duran well in command on the cards