NBA Players age like milk

The concept:

Players have a u-shaped curve in the NBA. The get better as they reach their 25th birthday. The peak around 25-26. After that they slowly decline as they approach 30 and after 32 they rapidly decline.

Why it’s important:

The concept of veteran leadership or presence is oft quoted in the NBA. The salary structure of the NBA also makes older players with more experience much more expensive. However, as their skills may be close to declining, they are a very risky prospect.

Background:

Dave Berri and Martin Schmidt first brought this concept up In Stumbling on Wins. Here’s a reminder from Stumbling on Wins how we expect players to change year to year as they age.

Player performance with age.
AGE CHANGE EXPECTED PERFORMANCE CHANGE FROM PREVIOUS SEASON
23 to 24 +2%
24 to 25 no change
25 to 26 -2%
26 to 27 -4%
27 to 28 -6%
28 to 29 -9%
29 to 30 -11%
30 to 31 -17%
31 to 32 -22%
32 to 33 -35%
33 to 34 -57%
34 to 35 -146%

Players peak around 25. Up until they’re around thirty their decline is slow. Once they hit thirty-two though their degradation is very swift. All of our greats are now in that range and some of them were already there four years ago.

When players age in sports it’s not a question of if they’ll stop being great it’s a matter of when. Sure some players can defy expectations but eventually even great players fall apart due to their age.