It is a tough one, if he had left Warren a few years ago and got himself into the world scene earlier he would have been as long as he stuck to 140lbs, the problem that he is not flexible and can only really be at his best at 140lbs will hinder him as the ATG's tended to be able to switch weights and not have many problems, but in saying that Marvin Hagler took 6-7 years before he really stepped up to the top fighters.
I think in the UK he will always be regarded as an ATG but on the world scene they haven't seen enough of him for him to be really remembered.
I think if he fights Oscar he will lose Oscar is just too big for him, but if he beat Oscar he will be up there, Pacquiao is so much smaller and Hatton has a good chance of beating him, but again it might be a case of too little too late.
UK ATG I think is his limit, and a good fighter worldwide, harsh cause I think he deserves more but Warren didn't get him the fights, like Calzaghe only now is he fighting the top names and getting recognition, beating a 43 year old Hopkins and a 39 year old Jones, probably won't get him up as high as he deserves as he spent most of his career fighting opponents who weren't world class.
Bookmarks