I have a problem with this. It's not useful to lump together the entire lineage of a sport then determine the best of all time, other than for ****s or giggles. This ignores the evolution (or devolution in some cases) of a sport over time. As sports grow and develop they change, rules are refined, standards are generally improved, goalposts are changed. If the sport becomes more popular then the overal level of competition increases, which in itself usually raises the bar. For example, there's just no way to say with any real conviction that Bob Fitzsimmons or Sam Langford are 'likely the two biggest punchers ever.' It's just an opinion and I could counter by saying that Jackson or Hearns are bigger punchers P4P. Who is right? They fought in different eras with different rulesets and mentalities. I think it's better to say that all 4 are among the hardest punchers P4P of all time. It's like in football - can you really say who was better between Pele, Maradona or Messi? I can't and I would argue that no-one really can. it's all just opinions at the end of the day.