My only problem with Leonard is that he had only 40 fights under his belt. Yes they were quality fights, but quantity counts too. I can't put Whitaker above Pac, he just hasn't done enough even if you were to say that he won over Chavez and De La Hoya.
No its a combo of everything, for me a big part of it is jumping from Fly to Welter. Name me someone who has done that? He continues to improve and yet he has already been great for a while.
Leonard squeezed enough quality into a relatively short career to be ranked in the top 15 ever. Whitaker was a four-weight champ, unified Lightweight and had an excellent run at 147 where he was linear champion. Personally I thought he drew with Oscar - and we all know he beat Chavez. At Lightweight, I thought Pea looked almost perfect - his performances against Ramirez, Haugen and Nelson were poetry in motion. Not to mention he was one of the greatest defensive fighters ever.
I haven't made a list but I don't think he has done quite enough to get in top 12. Definitely top 20, maybe even top 15, a win against Mayweather puts him well into the top 10 imo. So no, but there is a good chance he will be by the end of his career. I hope he doesn't hang up his gloves. Mayweather + Bradley on his resume would be incredible. Doubt that will happen though.