Barrera and Jones? Duran and a host of fighters? Hopkins and Taylor (although disputed)? Frazier and Foreman?
Barrera - emphasis on singular, as opposed to two sub-great fighters. If Barrera had two decision losses to (eg) Kennedy McKinney, he wouldn't be viewed in the same light. Duran had no unavenged losses in his prime. Hopkins was well past his prime against Taylor. Foreman is of comparable historical standing to Frazier, so don't see the comparison. With Mosley, you can throw in the loss to Cotto, the controversial second fight with De La Hoya, and the lack of HOF level wins on his resume. It isn't as if he has a host of great wins to counter-balance these losses. He's a HOF fighter based on a dominant LW run and the win over a prime DLH, but falls well short of being an ATG, regardless of how loose the term is defined.
I think the circumstances at 154 and surrounding his past-prime losses give him enough leeway to validate the string of solid wins he's got, but that's just me. Beating Oscar in the fashion he did sealed the deal from my perspective.
This is a problem I see happen time and time again when listing resumes. Somehow over the years, the insignificants of certain names and wins get forgotten and they startvgetting listed as meaningful fights and wins. Case in point, the Fernando Vargas fights. Those fights were against a completely shot vargas (especially due to his back and weight gains ) that it borders on the meaningless. It was a money fight through n through and vargas retired not too many fights later.
he has a very very good record. I would think it is a top 100 ATG record and maybe top 75. He lacks dominating wins over greats in my mind for a top 50 ATG ranking.