Say he did in a time period similar to Frazier. Started in around 66, retired as undefeated champ (in place of Ali, so there would be no Ali fight, but he would have fought up to around 73, allowing for a Foreman fight). Would you rank him as the GOAT?
I don't always put forth hypothetical questions But when I do I like them to be with Marciano beating Ali's competition!
He'd be fighting a well past prime Sonny Liston. Starting in 66. So he'd potentially have the likes of Zora Folley, Cleveland Williams, Floyd Patterson, Henry Cooper, Ernie Terrell, Karl Mildenberg, Jerry Quarry, Oscar Bonavena, Jimmy Ellis, Buster Mathis, Joe Frazier, Ken Norton and George Foreman. With some filler on his way up of course. That kind of list of names.
I think if Marciano went 49-0 in six fights between Liston, Frazier and Foreman at his size and with that style, plus the rest, I'd have to rate him above Harry Greb.
The quest is moot because he wouldn't have a snowball's chance in hell of going 49-0 then. The heavyweights were bigger and better in Ali's era.
Some were bigger but better? Was cooper better than rex layne? Was mildenburger better than kid mathews? Doug jones better than lastarza? Take the big guys, outside of (old) Liston you only have Williams and Terell . Who are Williams and terell in A.T.G terms? The Liston Ali fought was the only 50-50 fight out there for Marciano. Rocky was only ever going to last 4 years at the top in any era. If he starts in the cassius clay years then that conveniently takes Rocky out of circulation by the 1970s. Even so, those 1970s contenders are flattered by an older Ali and Frazier.