Mayweather vs Marciano: The insignificance of 48, 49 or 50-0

There will be much discussion the next two weeks about the relative significance in boxing history of 48-0, which is Floyd Mayweather's career record; 49-0, which was 1950s heavyweight legend Rocky Marciano's record; and 50-0, which could tease Mayweather in 2016 despite his insistence that his career won't extend beyond this year. As for comparing Mayweather and Marciano, have at it. They are among history's pound-for-pound greats. But 48, 49 or 50, and comparing raw records as if one fight eit…