I agree in part with this.... but it assumes sports don't evolve. "Boom Boom" Geoffreon invents the slap shot with a straight wood stick. Would he succeed and a day with hi-tech sticks, curved blades and wrist shots? No idea. The game is faster. Guys are mobile. Even within the last 10 years, some players body-types have fallen out of favor. Instigator rules hurt enforcers, so you have less guys there just to fight.
I agree that something made them great, but have we ever thought that maybe there are countless people today, NOT playing, but that could have played 100 years ago, when it was a part time gentleman's game? Maybe Babe Ruth would be an every day guy, not a 6'4" beast. Maybe guys who don't play now, because they wouldn't make it, would have been the super stars of 1935.
If you watch old games v. new, you know it's a totally different world now but it would be interesting to see if the greats were timeless, or just timely..