Go to youtube and watch the Duran - Barkley fight and then ask yourself if that were Pac in the ring, rather than Duran, how that fight would turn out. Duran took shoots that were far harder than the one that JMM threw and not once but numerous times.
duran won fights he was NOT supposed to at weights he was not supposed to be fighting at. pac pretty much had things in his favor with catchweights etc...in most of his matches. i think he'll go down as an atg...but not on the level or roberto duran.
When Pac beats a middleweight then we can talk, until then he's a great, great fighter but he's no Duran. Pac certainly doesn't have a prime SRL on is resume either. The biggest difference between them is that Duran is a far better fighter defensively. They likely would be fighting in a phone booth but Pac would be missing a lot and Duran would be countering and landing vicious body shots. But it would be a great fight for as long as it lasted.
in duran's defense...he started his career at 118....and won the legit title at 160 from the best middleweight champion at the time, iran barkley, without a catchweight. he also beat the best welterweight, leonard, without a catchweight.
Duran was the lightweight champ for 7 years and defended his title 12 times so how the hell you say he had no significant wins is a mystery to me. Most regard him as the best lightweight ever and at WORST he's the 3rd best.
It's a blight on his career that's for sure. But I don't see Pac fighting at middleweight and winning anytime soon either. Niether would Pac have beaten Leonard in the first fight. But if you assume we're talking about the peak version of each, then Duran wins a fairly competitive fight with his defense and better inside game being the difference.