If it wasn't for him beating Valuev a year and a half ago, Valuev would be 50-0. That would have been an insult to Marciano's record.
Chagaev did "serious" boxing fans a favour, that's for sure. The Marciano comparisons were already getting a little silly. Can you imagine the debates you'd have with casual fans "Apparently this big Russian guy is like the best boxer ever, 50-0, I think he'd even beat Ali and Tyson!" Blech!
Ugh. Nobody said Brien Neilsen broke the record when he went 50-0, only a moron would say Valuev broke the record if he had gone 50-0.