Great question. Will answer it a little later. Several great answers already too. My opinion is that Duran was truly at his greatest as a lightweight where he was intimidating, mean, and with vicious power and speed and will go down as the greatest in this division. But when he moved up in weight to 147 he remained an impressive fighter though he didn't fight at this weight fr that long but long enough to have fought in one of the biggest anticipated fights at that time vs Sugar Ray Leonard in which he displayed no respect or fear of Leonard and intimidating Leonard and taking the fight to him and so I can see where people would consider this his most impressive win because of the great fighter that Leonard was and Duran handing him his first career loss. So yes this would have to go down as Duran's most impressive win in his career in my opinion.
BQ: No because a younger Duran was only 135 lbs and nowhere big enough to have beaten Hagler of course and certainly not at welterweight either even as impressive as he was vs Leonard. Now if he could have been a natural middleweight instead of the lower weight classes with those skills, then I would say yes he could have beaten nearly anyone including Hagler.
Absolutely!
He was a Lightweight Champion jumping straight up to fight the best Welterweight of that era and clearly beat him. Also, this wasn't just any Welterweight...this was undefeated future Hall Of Famer Sugar Ray Leonard. Not only was he a great fighter but he was extremely high profile. Beating Leonard in the place Leonard won his Olympic Gold Medal in his first fight 14 pound north of Welterweight was very impressive and hard to beat.
BQ: NO. Duran was at his best at Lightweight. Even when he was a Middleweight, he wasn't naturally so. Hagler was always a Middleweight and one of the best to ever enter a ring. The size difference would favor Hagler 45 out of 50 times
I think so. He fazed and intimidated SRL for most of the early to middle rounds with his famed hand of stone, even buckling the American's knees with one shot forcing him to hold on for dear life. When SRL somewhat managed to regain his confidence and composure, Duran took the best shots and worst whaling SRL could dish out without flinching and clinching. By the championship rounds, the Panamanian had again gained control of the fight leading to that undisputed 15 round UD.
It was a complete, thorough, masterful win by the Panamanian bomber against a supposed master boxer.
Yes, it was all the more impressive considering that he went up in weight (135 to 147) to challenge the welterweight champion and current golden boy and toast of the sport of boxing and eventually brought him down to earth.
BQ: If a younger Duran fought Hagler could he have beaten him?
