Park Factors
Today-only MLB matchup context using home-park conditions, weather, time of day, and season position.
How Park Factors Are Computed
What it measures: How much a park amplifies or suppresses pitcher strikeouts vs. the league average (1.00 = neutral). A factor of 1.05 means pitchers at that park record ~5% more Ks than average for the same pitcher quality.
Method: We aggregate pitcher strikeouts and batters-faced from BDL regular-season games at each venue (2024–2026), compute league-average K rate, then derive a raw park K rate ratio. Small samples are regressed toward a FanGraphs-calibrated prior with ~2,000 PA of weight. Dome/retractable-roof parks show more stable factors since weather doesn't contribute.
Model usage: The park K factor is applied as a λ multiplier in the Poisson strikeout model alongside weather, age curve, whiff%, opponent K%, home field, and umpire zone tendency.
Weather-adjusted park factors update every 30 minutes.