Gentile: Baseball’s youth movement as told by WAR

From James Gentile at Beyond the Box Score on January 31, 2013:

Last week Ari Berkowitz wrote an article here at Beyond the Box Score exploring the reasons why Major League Baseball seems to be trending younger in recent seasons. While Ari showed that the average age of ballplayers is on a steady decline since 2004 or so, I was curious how Baseball-Reference’s WAR might view the changing of the tide.

I grouped position players into four (admittedly) generic age groups, 21-25, 26-30, 31-35, and 36-40 from each season since 1900 and added up all the WAR earned by each age group. (In earlier versions of this chart I did leave in the “20 and younger” group as well as the “40 and older” group, but as it turns out neither has been very relevant).


The game has gone through many changes over the years, but the 26-30 age group has generally brought home around half of all position player WAR, especially since WWII. This group essentially represents the bread and butter of batters in the league, while the 21-25 and 31-35 groups seem to have been battling for superiority over the other for nearly the entire span of baseball’s history.

We see the exact trend Ari referenced in his article when examining the 2005-2010 time frame, where the age 21-25 group has been steadily on the rise. But what we may often overlook is that this recent triumph of youth is really just a return to baseball’s status quo beginning in the 1960’s up until the onset of the 1990’s.

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Originally published: January 31, 2013. Last Updated: January 31, 2013.