Batting Average on Balls In Play (BABIP)


Batting Average on Balls in Play (BABIP from here on) is an important stat to look at, from the sabermetrical perspective. It is also wrapped up in some concepts that can feel counterintuitive to many baseball fans, namely that of dumb luck. Not that we as baseball bingers aren’t all familiar with the blop single off of a nasty two-seamer that beats our team in an extra inning walk off. Nope, we’ve all had our hearts stomped on by lady luck, and likely all called her names unbefitting of a lady. Let’s lay it on out there what BABIP is, and then explore why this oddly-fun-to-say acronym should matter to all of us heartbroken baseball geeks.

BABIP is just like Batting Average, except that it is vegan and only drinks craft beer. You see, to calculate BABIP, we don’t consider just any ole at bat. We painstakingly narrow it down to only outcomes in which the ball was hit in fair territory (also called “balls in play”), not including home runs and sacrifice bunts (sacrifice flies DO figure in). Then, we simply calculate the average number of these balls in play outcomes that were hits. It works just like a batting average, but only on balls that were hit in fair territory and didn’t have the distance for a dinger. Full disclosure: I think veganism is totally reasonable, and I love craft beer.

So why do we care about such a high maintenance statistic? Well, because we want to separate luck from skill, and the skill of the defense from the skill of the pitcher. Let’s lay this thing out. Around 30% of balls in play are hits, historically. This can affected by the skill of the batter or pitcher, the skill of the defense, and luck (not to mention park affects, weather, etc, but let’s just group that all in with luck). So some hitters and pitchers will have better BABIPs simply because of their skill set (fast runners and line drive hitters, for example). However, a BABIP that has suddenly shot up or down for a player, even over the course of a whole season, should make us suspicious that luck is clouding the player’s performance one way or the other. We’ve all seen guys who seem to go through periods hitting the ball hard and having nothing to show for it, even full seasons. Luck’s a real factor in baseball, and we can’t ignore it. Now, I mentioned defense too. If a pitcher plays in front of a great defense, say, maybe one with Adrelton Simmons at shortstop, that pither is likely to see some benefit in the form of a lowered BABIP. More balls put in play end up outs. We should be aware of this when we are comparing the performance of pitchers from different teams. This matters for big league clubs, too; “should pay this free agent pitcher what he wants based on his numbers while pitching in front of a great defense? Our defense stinks!”

So there you go, BABIP is a great and pretty simple tool that (1) gives us a glimpse into what may be causing streaks of one sort of another, and (2) helps us understand a players skill set, especially when we incorporate other batted ball data like ground ball / fly ball ratio, and the like. You can find just such information and more on BABIP right here, over at FANGRAPHS.

If you’re interested, here is the equation:

Screen Shot 2015-09-12 at 6.44.44 PM

Further reading from…


A Beginner’s Guide of sorts, on fast players and BABIP, and Age and BABIP

Buckner photo courtesy of Buzzfeed.

[Note: we are currently updating the site, GrizzlyBear.jpg with us!]

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