Top 20...That is if he retires undefeated. An unbeaten 5 weight division champ, few HOF fighters and a top 20 ATG in his resume in Pac(prime) has to be a big boost. Now if he goes on to beat Mosley, Williams id have him top 15.
I'm not going to get into ATG ranking anymore. It's pointless 'cause nobody can get near the classical fighters no matter what they do. I will rank him as one of the top 5 super-featherweights of all-time. I cant really find anything more meaningful to attribute him just 'cause he beats Manny PAC at welter.
If he beats Pac in a brutal fashion, first I would say kudos to Floyd Mayweather. Second, he is would probably be in the top 30. If he fights and cleans the welterweight division top 20 depending on how he does.
Top 15. That wud be 15 world champions on his resume and pac is a 7 weight champion and ATG himself. Floyd wud have 7 world titles in 5 different weights and once again be universally recognised as p4p best in the world. IF he cleans out WW top 10 easy.
