Batting average on balls in play

Calculation

BABIP is computed per the following equation, where H is hits, HR is home runs, AB is at bats, K is strikeouts, and SF is sacrifice flies.

BABIP = \frac{H-HR}{AB-K-HR+SF}

Effect

As compared to batting average, which is simply hits divided by at bats, BABIP excludes home runs and strikeouts from consideration while treating sacrifice flies as hitless at bats.

In Major League Baseball (MLB), .300 is considered an average BABIP. for batters, being speedy enough to reach base on infield hits;

Leaders in Major League Baseball

For major-league players, the .383 BABIP of Ty Cobb is the highest for a career (players must have at least 3,000 career plate appearances to qualify). Cobb also holds the single-season major-league record, having posted a .444 BABIP during the season (players must have at least 3.1 plate appearances per team game played to qualify).

Usage

BABIP is commonly used as a red flag in sabermetric analysis, as a consistently high or low BABIP is hard to maintain—much more so for pitchers than hitters. Therefore, BABIP can be used to spot outlying seasons by pitchers. As with other statistical measures, those pitchers whose BABIPs are extremely high (bad) can often be expected to improve in the following season, and those pitchers whose BABIPs are extremely low (good) can often be expected to regress in the following season.

While a pitcher's BABIP may vary from season to season, there are distinct differences between pitchers when looking at career BABIP figures.

References

References

1. Reinhart, Brian. (June 4, 2013). "The Ten Highest BABIPs since 1945".
2. Slowinski, Piper. (February 10, 2010). "BABIP".
3. Eriq. (May 18, 2010). "The True Nature of 'Luck' For Pitchers".
4. "Highest Career BABIP".
5. "Highest Single Season BABIP".