Park factors: where you play matters
Same swing, same ball flight — home run in Cincinnati, flyout in San Francisco. How do stats cope?
Ballparks aren't standardized. Fences sit at different distances, foul territory varies, and air matters enormously — Coors Field's altitude inflates scoring ~10–15%, marine air in San Francisco suppresses it. Thirty 'identical' seasons would produce visibly different stat lines across thirty parks.
The correction
A park factor compares scoring in a park to the league norm: 110 means offense plays up 10% there; 95 means it plays down 5%. Adjusted stats (next lesson) bake this in, halving the factor for hitters since they play half their games on the road.
The reflex to build: before praising or dismissing any raw stat line, ask where it was compiled. A .270/25 HR season in a canyon can be more impressive than .290/32 at altitude.
How this stat lies to you
- One number per park hides that parks affect lefties/righties and HR/doubles differently.
- Factors drift — weather years, fence moves, humidors. Multi-year factors are safer.
- Players aren't averages: an extreme fly-ball hitter feels a short porch far more than the park factor implies.
Check yourself
1. Park factor 108 means…
2. Two identical .850 OPS seasons — one at Coors (PF ~112), one in a 95 park. Which hitter was better?