This is the one thing that makes the agruement of who is best all time both fun and so upsetting.
How would some of today's guys liked being thrown to the ground as they went up for a lay up every time?
How would some of the older guys handled being able to get the extra step and not being pushed on all the time?
The biggest one I think the difference is in strength and nutrition. Think about it Jesse Owens was the fastest man in the world, he ran on a cinder track, dug holes for starting blocks and wasn't allowed to eat in more than half of the in restaurants in the country that he lived in.
I know that Bolt only ate chicken nuggets in Russia or where ever but he still has had reaaly good food up to that point I would think.
Think about injuries. Old timers who careers where done with injuries that now can be fixed and you can come back better and stronger.
I think a lot of people don't really think about some of these things when they look into say who was the best ever in any sport, I try to at least throw that in when I get into these agruements.