I cant really think how to phrase this but with nutritional advances, diet technicians, all of these NEWER things being introduced to the sport at what point in history does it become unfair and null to compare fighters in an actual fight -

for example Joe Louis - was new physical conditioning, training methods, legal supplements etc so advanced by the time of Ali, Frazier, Foreman, Norton, Hell even Liston came along that they would likely have all beaten him if they had put the two fighters in the ring at their peak with Louis training 30's style and the others 70's and subsequently if we put any of them in with lewis, klitscho etc would they be disadvanatged massively by the subsequent advances in techniques, supplements etc

Also where does the line cross!?. I.e. an 84 holmes or an 88 tyson who are somewhere in the middle -

A badly written post but hard to frame and explain my question!