Assume that nobody has ever seen any footage of a current fighter, or any of their opponents. There only defense of their career is Boxrec! How do the current top tens hold up?
Floyd Mayweather, Joe Calzaghe, Lennox Lewis, Oleksandr Usyk, Rocky Marciano, Joe Louis, basically anyone with a good win/loss ratio
If we had never seen (or heard about, I assume?) any of today's fighters - we would probably conclude, that Chayaphon Moonsri must be the best boxer in the world.