David Biderman of the Wall Street Journal has a short story today on the aging of NBA players. The article notes that the peak age – or the point where player stop improving – is around 24 or 25 years of age. Biderman’s source for this story is some economist from Southern Utah University.
The research Biderman sites will be discussed in Stumbling on Wins (which should be shipped to bookstores in February or early March). Since everyone doesn’t have access to our book just yet (although we hope that changes for everyone – and we mean everyone – soon), let me offer a few observations.
Via a study of NBA players from 1977-78 to 2007-78 (a study discussed in more detail in the book), we found that an NBA player generally improves until he is in his mid-20s. Performance after this point is not much different until a player reaches about 27 or 28 years of age. After that point – and especially when a player passes the age of 30 – performance starts to decline more noticeably.
It’s important to note…
- we are reporting a tendency. The peak at 24 or 25 will not be true for every player. But when you look at the link between age and performance, controlling for a host of other factors, the general peak is in this range.
- the results were the same when we looked at NBA Efficiency. So this result does not depend on looking at performance via Wins Produced.
- the key issue is not the specific point in the player’s 20s where the peak occurs, but rather that performance after age 30 has a noticeable drop-off. In the player’s twenties the slope downward is quite gradual (and not something you would probably notice if you watched the player). In other words, LeBron will still be LeBron – barring injury – for a few more years.
Let me also add that the drop-off after age 30 will not be the same for everyone. For some players, performance declines considerably (as my post on Kareem and Shaq noted a few days ago). However, John Stockton posted a WP48 of 0.262 at the age of 40 (Stockton’s best season, though, was at the age of 25).
And one last note…JC Bradbury had a very interesting article on this subject in the context of baseball. One issue Bradbury emphasized is that more athletic activities (like tennis, short distance running, and swimming) tend to see peak performances at a very young age. In a sport like golf – and with respect to some aspects of baseball – peak performance occurs much later. Basketball is a sport that relies tremendously on athletic ability, so we shouldn’t be surprised to see a peak in the mid-twenties (as opposed to a point closer to 30 years of age).
Again, we have more on this in our next book (which you can already pre-order at Amazon.com).
– DJ
The WoW Journal Comments Policy
Our research on the NBA was summarized HERE.
The Technical Notes at wagesofwins.com provides substantially more information on the published research behind Wins Produced and Win Score
Wins Produced, Win Score, and PAWSmin are also discussed in the following posts:
Simple Models of Player Performance
What Wins Produced Says and What It Does Not Say
Introducing PAWSmin — and a Defense of Box Score Statistics
Finally, A Guide to Evaluating Models contains useful hints on how to interpret and evaluate statistical models.
Wages of Wins Journal 
simon
December 23, 2009
Of course, Biderman conveniently “forgot” to mention that fact that the decline is quite gradual until the late twenties.
todd2
December 23, 2009
Some have argued that productivity generally peaks between the ages of 25 and 30. Einstein published his theory at 26.
Rob O'Malley
December 23, 2009
I believe Newton came out with calculus around his mid 20s
dberri
December 23, 2009
Dave Berri co-authored Stumbling on Wins at the age of 40. So peak for a sports economist must come later (relative to someone in physics).
JAW
December 24, 2009
DB, perhaps this will be in the book, but the aging curves have to be different by position, no? Anecdotally I would guess centers peak earlier, and point guards peak later, but again, that is anecdotal.
Did you look into again patterns for various skill sets? That’s one thing I found fascinating in Tom Tango’s work on baseball aging patterns. While we all know baseball players peak at 27 on average, there’s some difference in aging depending on their specific skill set (high K/high BB vs. low K/low BB for example).
todd2
December 24, 2009
Did some digging—Robert Parish averaged 12 points, 7 rebounds and 49% at 40. Not bad for an old goat.
khandor
December 24, 2009
David,
Here’s a two-part question for you to consider:
Part I
In your opinion, is it possible for a great player to produce indivdual performance numbers that are “less than” [below] his peak values … which, according to what you’re saying here, usually occurs in the mid-20’s … while he is actually continuing to improve as a basketball player [i.e. from his mid-20’s to his later 20’s and even his early 30’s]?
My answer to this specific question is, “Yes.”
Part II
If the correct answer to this questions is, in fact, “Yes,” then:
What does this actually say about the qualitative value of the individual performance numbers generated by this type of athlete during his mid-20’s vs those numbers generated by him during his later 20’s and early 30’s?
Eyal
December 26, 2009
Does the number of years in the league mean anything? Would a player who started in the league at 18 peak at the same age as someone who was a rookie at 24?
Jim Glass
December 26, 2009
JC Bradbury had a very interesting article on this subject in the context of baseball. One issue Bradbury emphasized is that more athletic activities (like tennis, short distance running, and swimming) tend to see peak performances at a very young age.
I think “athletic ability” could be more fully defined, as it has many components.
I.e.; Quickness, speed, and strength are different elements of athletic ability, but I’d guess they have different “up” and “down” rates.
E.g., I’ve seen studies of how quickly NFL players “age” by position, with running backs who depend on quickness, instinctive reflex reactions and speed having the shortest careers while OL players who depend on strength and technique keeping on making all-pro well into their 30s long after near all RBs are gone from the game. And other positions being in the middle, depending on their ratios of instintive quickness-and-speed to strength-and-smarts that they call upon.
Mental training might be thought to feed into things too, by improving physical techniques.
As for pure mental ability, “Einstein at 26”, the first objective, empricial study I saw of “age peaks” and decline rates was by Dr Aprad Elo when he put together the rating system for chess players 30-odd years ago. (The “Elo ratings” since adopted for many sports and competitions, including even rating colleges by admission results. )
It found a pretty uniform peak at around age 28-30 for near all, but a very wide dispersal of decline rates, ranging from some players falling off a cliff right then to others playing on into their 60s at barely below their peak level.
Of course, chess uses a limited set of mental skills, primarily pattern recognition, calculation and quick operating memory, which — like quick reflexes among sports players — might decline a lot faster than other skills.
Good economists who gain ever-more wisdom, knowledge, and judgment with advancing age, and who work on computers with ever faster processing speeds that compensate for their own slowing mental calculation powers, may just get better and better and better…
Jim Glass
December 26, 2009
Sorry for the misformated link in my prior comment.
(I wish the comments here had a “preview” function.)