This was definitely a thing just back in the 2000s. You had guys like melo, tmac, Paul pierce, wade, Dwight ect all decline in this age range or way before. People always mentioned lebron still being so good when he was 33. At first that seemed like an anomaly. Now, you have guys like curry, kd, kawhi, dame, lebron still(lol) jimmy butler, all still being in their prime at 33+. Is it an advancement in technology and medicine? Something else?
NFL rules shifted between the 90’s and early 2000’s that provided a significant advantage to the passing game with stricter enforcement of pass interference rules, tackling rules, and handling of the quarterback. Comparing what Steve Young and Brett Favre played through to Peyton Manning, Drew Brees, and Tom Brady faced is almost apples to oranges.