Baseball is filled with statistics, rules, and archaic terms that can often form what sounds like a foreign language. Sons of Sam Horn’s glossary provides a better understanding of these terms through straightforward definitions, clear explanations, and examples pulled straight from the baseball world. If there is anything you would like us to add to our glossary, please contact us.
Batting average on balls in play, or BABIP, measures how often batted balls fall in for hits. The results can vary based on three main factors: skill, luck, and defensive performance. Over a large sample size, BABIP tends to end up near league average (.290-.300), while hitters have more variance and their individual skill may be seen.
How BABIP Is Calculated
Batted Ball Profile
Whether dealing with a batter or pitcher, it is important to note the split between line drives, ground balls, and fly balls that the batter hits or pitcher gives up. Line drives fall in for more hits than ground balls, while ground balls result in more hits than fly balls. Therefore a hitter with a higher-than-average line drive rate can be expected to have a higher-than-average BABIP.
Using BABIP With Batters
Hitters have more control over their BABIP than pitchers because of the force they can exert on the ball when striking it, and their foot speed (or lack thereof). Studies have shown that batting average on balls in play tends to normalize with hitters after around 800 batted balls, or about one-and-a-half to two seasons. If a hitter is struggling and hitting well below his normal BABIP, then you can reasonably assume that it is bad luck or that he has run into a string of good defensive performances. Going forward that hitter should perform to his career norms when it comes to BABIP. A word of caution: This only means that his BABIP from this point forward will be at his career average, not that his year-end numbers will match that of his career average.
Using BABIP With Pitchers
Pitchers have far less control of their BABIP when compared to hitters. Because of this, pitchers’ BABIPs tend to sit around league average, which is .290-.300. Pitchers’ BABIP takes around 2,000 balls in play (or three seasons for a starter) to normalize.
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