He was a good inside fighter even earlier than lightweight. Watch the Jesus Chavez fight and watch Mayweather throw those nice uppercuts on the inside and deflect all of Chavez' shots not eating them like Taylor did. http://youtube.com/watch?v=Fco0PmJX8bw
I'm sure you've seen Whitaker/Chavez plenty of times, but you might want to watch again. Whitaker fights Chavez in a manner that's more like Mayweather's normal style than his own reagular style. Whitaker normaly a slick boxer takes the fight to Chavez. Chavez was out of his elelement. Your right Chavez was at his best at 130, but so was Mayweather.
He wasn't past his peak, he looked amazing against camacho only a few fights ago. Just because he got schooled by a higher caliber of a fighter doesn't mean you can use the "out of prime" excuse. Chavez began to drink among other things right after the Rosario fight but went on to beat Taylor.
Chavez had been a world championship level fighter for nearly a decade. He looked brilliant against Camacho and Haugen but clearly wasn't the same and you can see it by comparing his results against the second tier guys. Look at something like the Dwight Prachett fight and then against Angel Hernandez and the difference is quite clear.
While this is true, Whitaker was much closer to his peak than Chavez being younger, closer to his best weight, and having many fewer fights. Or to put it another way: Chavez won his first title before Sweet Pea had his first pro fight.
Julio Cesar Chavez would be the best offensive AND defensive fighter Floyd has ever fought. Julio is not Jesus Chavez, he isn't going to wade in with a sloppy infighting game and just wail away and tire himself out whilst Floyd counters everything he throws. Chavez will apply educated pressure, manoeuvre Floyd towards the ropes and bank on landing more than Floyd, who even at 130 had a tendency to pot shots and throw one punch at a time. Mayweather's infighting ability at 130 is not nearly as refined as it is now, and I'm not sure I would even favour Mayweather if he had that infighting ability refined back at 130 - because Chavez is still better there at that caper. A close fight, but I struggle to see Floyd winning more rounds.
Whitaker didn't allow himself to get stuck on the ropes once in that fight. I give Mayweather maybe a round and a half before he finds himself there.
I agree with you. But the problem is that he doesn't throw enough punches to buy space, and isn't varied enough in his upper body movements to keep a fight at ring centre with Chavez.