Era adjustment is made via Full House Modeling. This model computes era-adjusted statistics through a principled balancing of how well a player performed "vs their peers" and the size of the MLB talent pool.

We present an updated version of the website with:

• New talent pool calculation. This estimate is similar to the previous version. The main change is that we change the reference group from aged 20-29 eligible males to aged 20-29 eligible white males. Results do not change too much. The change allows to also calculate a talent pool for the Negro League!
• More robust tail probability modeling in the fullhouse package.
• New stats: 2B, 3B, SLG, OPS, JAWS
• Data through 2025 season
• Better UI, comprehensive leaderboards with stat download, and player-specific linking

We present an updated version of the website with:

• An updated writeup that highlights some results and discussions based on our era-adjusted statistics.
• Data through 2024 season
• Better UI on mobile devices
• Added loess smoothing of home run counts for Dead Ball era players

We present a new version of the Full House Model with:

• A new and better justified estimation of the talent pool over time
• Version 2.0 of a detailed writeup that highlights some results and discussions based on our era-adjusted statistics.
• A technical report that goes through important calculations and additional analyses
• Data through the 2023 season
• Removed rotation adjustments
• Removed smoothing

The app contains several era-adjusted statistics for baseball players which are obtained from the Full House Model. This model computes era-adjusted statistics through a principled balancing of how well a player performed "vs their peers" and the size of the MLB eligible population. Under this model, great all-time statistics requires that an MLB player is both better than their peers and played during a time in which the MLB eligible population is large. In this way, the model constructs an even playing field that extends across eras.

For a fun read on the Full House Model see our three-part series: article I, article II, article III

Our original estimation of the talent pool can be seen here.