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Definition – What is Batting Park Factor?
Batting Park Factor measures the impact of a specific baseball park.
A batting park factor over 1 favors the hitter, while a BPF under 1 favors the pitcher. The further the number is from one, the more heavily it favors either the hitter or the pitcher.
The metric can also be interpreted a a team’s style of play at home compared to on the road, or as evaluating different baseball parks for their offensive or defensive friendliness.
Formula – How to Calculate BPF
A = (Runs Scored at Home + Runs Against at Home) ÷ Home Games
B = (Runs Scored while Away + Runs Against while Away) ÷ Road Games
BPF = A ÷ B
Example
If team has the following statistics:
Home: Games – 158 | Runs Scored – 790 | Runs Against – 780
Away: Games – 139 | Runs Scored – 841 | Runs Against – 891
then:
BPF = ((790 + 780) ÷ 158) ÷ ((841 + 891) ÷ 139)
BPF = (1570 ÷ 158) ÷ (1732 ÷ 139)
BPF = 9.937 ÷ 12.460
BPF = 0.798
Therefore, the team’s Batting Park Factor is 0.798, or 79.8%.
Sources and more resources
- Wikipedia – Batting Park Factor – Wikipedia entry on the concept of batting park factor.
- Batting Park Factor data from ESPN.
- Rules on baseball and baseball statistics from Major League Baseball, NCAA (Baseball), NCAA (Softball), NCAA (Baseball and Softball), NFHS, and the International Baseball Federation.
- A discussion on park effects with Jesse Siegel – “Ballpark Factors: Analyzing Park Effects of the 30 Stadiums,” The Hardball Times – “Batted Balls and Park Effects,” Baseball Reference – “Park Adjustments,” Beyond the Box Score – “Methods Section – Creating Your Own Park Factors,” and Joe Blogs – “A bit more math: Park Factors”