These arguments always end up leading to nowhere imo because everything has to be kept in perspective and its impossible to compare across generations.
Anything before the last 20 years is hard to even put in perspective because of rules changes, evolving offenses, strength and conditioning, nutrition etc, not to mention massive steroid use that went undetected in those earlier decades(Hi 227lb Bo Jackson that ran a 4.13.. Seems legit! Bo knows testosterone?). Then you also have to consider this isnt tennis in a vacuum since there are 10 other guys out there on offense too and even a great defense can inflate an offensive players numbers (who can get you the ball back more if they're good). Would Steve Young be shit all today if he had never left the creamsicle Bucs team he was supposed to play for in 84 and had a career stuck with those players instead of the 49er legends? Now the front office comes into play....so much of it is dumb luck.
I remember one of the Steel Curtain teams talking about how the night before the Super Bowl (that they won btw) they were out at bars getting drunk and smoking cigarettes cigars and shit in the wee hours of the morning before the game. 99% of those guys wouldn't even make the 53 man rosters of NFL teams in this day and age if you had a time machine to put them in 2020 -- hell prolly not even the practice squad. You'd have the top guys with dad bods in the 70s vs freaks of fucking nature like DK Metcalf.