Altitude, fences, and dimensions shape scoring
Coors Field in Denver sits at 5,280 feet elevation where the thinner air allows baseballs to travel farther and faster, boosting offensive output. Petco Park in San Diego has expansive dimensions and coastal winds that suppress home runs. Park factor normalizes these effects into a single multiplier: 1.0 means average park effects, 1.15 means 15% more runs than league average for that ballpark in that season, and 0.85 means 15% fewer.
Knowing park factors is essential for comparing players across stadiums. A .280 hitter in Denver may actually be a .265 hitter when adjusted for park, while a .280 hitter in Petco is truly hitting .295.
Season-specific adjustments matter
Park factors vary by year due to weather patterns, wind direction changes, and fence reconfiguration. Using a single park factor across multiple seasons misses this variation. Modern baseball analytics recalculate park factors annually, feeding them into player-comparison systems and trade valuations.