Young And Relentless: The Face Of MLB Keeps Getting Younger

Breaking those 25 complete seasons since 1998 into buckets of five years, we see a clear trend emerge.

Share of PAs by players aged 24-28
1998 to 2002: 41.3%
2003 to 2007: 39.1%
2008 to 2012: 44.6%
2013 to 2017: 44.0%
2018 to 2023: 50.1%

Broadly speaking: Players aged 24 to 28 accounted for roughly 40% of all MLB plate appearances for the first 10 seasons of the 30-team era. That figure rose to roughly 45% of PAs in the second 10 seasons. 

Now, in the first five seasons of the third decade of the 30-team era, representation by players aged 24 to 28 has risen again, this time to roughly 50% of all PAs. 

MLB teams are concentrating more and more playing time on players in their mid to late 20s for myriad reasons.

(1) Players in their mid 20s are at their athletic peaks. On the whole, the players contribute stronger defense, especially up the middle, and greater basestealing value. The recent MLB rules changes may exacerbate the trend toward younger players because of the premium placed on speed and defensive range. 

(2) Younger position players tend to lose fewer days to the injured list than older players. Additionally, the scaling back of performance enhancers and stimulants since drug testing began in the mid 2000s also tilts the scales toward younger players, whose bodies naturally recover more quickly. These factors bias the overall data toward youth. 

(3) It’s the money, stupid. The MLB pay scale values experience above all, so pre–free agency players in their 20s offer payroll certainty to clubs. Even arbitration raises can be forecast accurately. The best players in their 20s will generally continue playing into their 30s, while players below this tier are phased out.

Observations on the graph above:

• Players 28-and-under account for roughly 60% of all MLB plate appearances, a level first reached in 2018. In the 30-team era, this 28U share has been as low as 44.6% in 2005.

• In the same 2018 to 2023 period, the share of PAs by players 34-and-older has decreased each season, from 10.2% at the beginning of the sample to 7.7% in 2023. This 34-and-older share climbed as high as 17.4% in 2006.

• The extremes have become more extreme. As the bucket of the youngest position players has grown larger, the bucket of the oldest players continues to shrink.

Everything Is Cyclical

One interesting aspect of playing time trends by age is how the position player “golden hour” has cycled between ages 26, 27 and 28 in reliable three-year patterns.

Ever since the 2010 season, this cycle has repeated. In Year One, 26-year-olds take the most plate appearances. In Year Two, it is 27-year-olds who bat most often. In Year Three, 28-year-olds have their turn. 

Then everything resets.

This three-year cycle has started anew in 2013, 2016 and 2019. After the shortened 2020 season, the cycle reset with 2021, when 26-year-olds took 14.1% of all plate appearances. This is the highest share of playing time for any age group since 1998.   

The position players who were 26 in 2021 continued to play most often as 27-year-olds in 2022 and 28-year-olds in 2023, accounting for shares of 13.6% and 12.8%, the largest in those given seasons. 

If the cycle resets in 2024, then 26-year-old position players will once again accrue the most playing time. This is a strong possibility in light of the fact that players 25-and-younger accounted for 28.2% of plate appearances in 2023, which is the highest share for that group in the 30-team era.

In other words, MLB could be on the verge of a young man’s game becoming even younger.