Linear Weights & Run Expectancy

Every advanced metric on this site rests on these numbers. We replayed 618,310 play-by-play rows through a state machine to recover the base-out situation before every plate appearance, validated the reconstruction against charted games (91% on base state, 95% on outs), and fit run expectancy and linear weights on the resulting 406,949 plate appearances.

The headline: softball's run values are not baseball's. A home run is worth 1.88 runs here, a walk 0.82, and the wOBA scale comes out at 0.97 against a league OBP of 0.374. A stolen base adds +0.22 runs and a caught stealing costs -0.62, which puts the break-even success rate at 74 percent. Anyone importing MLB constants into softball analysis is measuring the wrong sport.

The full 24-state run expectancy matrix is below and in the download, alongside the weights in both CSV and JSON. These feed directly into our WAR framework.

This dataset is free to use under CC BY 4.0: use it anywhere, including commercially, with attribution to Pioneer Pennant (pioneerpennant.com).