How come Duran hurt Leonard in Round 2 of their first fight more than Hearns did?

"That name 'Manos De Piedra,' that's true. 'Hands Of Stone.' Every punch that he hit me with felt like Bricks... Stone... Rocks." - Sugar Ray Leonard

 

One character was scary looking but you could at least understand the words that were coming out of his mouth and the other had no care or respect for you or your wife.

 

Because the age old, but very true theory "Styles make Fight's".

 

Balance and luck.
Duran rotated the weight of his whole body into the punch and caught Leonard while he wasn't expecting it.

For the rest of the fight, Duran sapped Leonard's strenght during the infighting, because Leonard closed the distance and allowed him to work.

Leonard was expecting Hearns punches; Hearns couldn't get the same leverage on his punches than Duran on the inside.

 

in boxing, logic like this often fails.

How come the bigger puncher didn't hurt him as much as the other guy? doesn't work.

 

Hearns rarely threw with conviction, considering he was on the move from round 7 on after feeling Ray's power and being hurt himself. He resorted to more of a boxing and moving mode afterwards, while Leonard stalked with his high guard to avoid the brunt of the incoming blows.

Duran, on the other hand, was just a better fighter than Leonard that night, and had him damn near outclassed when he was doing his best work (though Leonard would eventually come on down the stretch while Duran started to coast on his lead, which by the 12th or so was pretty sizeable IMO). It wasn't so much the raw power behind his punches as the body put into them, the accuracy, and the craft with which he threw them, often catching Leonard off guard or off balance, after which he'd catch himn in a bad situation along the ropes and go to work on him in the inside. His in-fighting that night was the best I've ever seen bar none. If you haven't seen that fight in a while, I suggest you study his work that night. Crack open a beer, pull out a joint, whatever, and just study Duran's in-fighting and especially his clinch-fighting, which was far from a detriment to the fight.