While comparing generational changes in athletics, you could dismiss yesteryear's heroes for playing during segregated eras. Or, you could just watch some film of 1940's basketball players, with belts in their shorts and pomade in their hair, and quickly reach the conclusion that most of these guys wouldn't score in the YMCA men's leagues of today. Your dad probably goes nuts about "real football" after every roughing the passer penalty, but back in his day linebackers topped out at 220 pounds and smoked Winston cigarettes on the sideline. Y.A. Tittle's a little banged up here, sure; he wouldn't even make it to his knees if he was playing with James Harrison.
Most past legends wouldn't touch the field today.