As a fully fledged member of the lower middle classes I take great offense to that. You'll be hearing from my solicitor.
Brian Nielsen went to 49-0. And he also had wins over Holmes and Witherspoon (both well above 40 at that time). So you can see that fighting past prime greats and padding your record doesn't make you an ATG.
He is a fighter that wouldn't beat any other all time great prime for prime. Many thought he lost to Hopkins, others thought he lost to Reid. Calzaghe was one of those guys who was content to sit on his laurels and fight chump after chump because he was getting nice purses from the live gates over there in the U.K. When your best opponents are a 43 year old Hopkins that gassed half way through the fight, and Kessler... For a upper level guy, that type of resume leaves a whole lot to be desired.
Calzaghe is indeed an ATG. If we list the top 5000 ATGs, we surely can squeeze JC at the tail end of that list.