Sorry, but this is utter nonsense.
There are lots of reasons for improved performance - evolution isn't one of them. You don't evolve significantly in a 3 or 4 generations.
Exactly. 80 years is two or three generations, which in evolutionary terms is nothing . Instead, the difference between players today vs. 50 years ago is more related to things like access to better nutrition, healthcare, environmental factors, weight training, etc.. much moreso than evolution.
Beyond that as alluded to by Reddick who apparently tried to use it as a slight, it’s true many early athletes held second jobs. That’s because they weren’t paid the insane amounts of money that todays athletes are paid so they couldn’t afford to dedicate their life around playing one sport for part of the year and not worry about paying the bills the remainder of the time like athletes of old had to.