Daily Dictionary: Batting Average on Balls In Play

Batting Average on Balls in Play (BABIP)

BABIP = ((hits - home runs)/(at bats - strikeouts - home runs + sacrifice flies))

BABIP measures the percentage of at-bats that hitters get or pitchers give up when the ball is put in play. We're starting the baseball analysis here because it is an important part of baseball analysis. Hitters and pitchers both have relatively little control of what happens once the ball is put in play (we'll look at this below). BABIP basically measures how lucky or unlucky a hitter or pitcher is over a smaller sample size. BABIP is proven, over a long example, to be very consistent among all pitchers. BABIP varies a little more among hitters, mostly among fast hitters who can beat out more infield hits.

Roy Halladay career BABIP: .292

Roger Clemens career BABIP: .284

Randy Wolf career BABIP: .284

Kevin Appier career BABIP: .284

So, Kevin Appier and Randy Wolf were equally as good (or better) as/than Clemens and Halladay at batting average on balls hitters put in play against them. Like it was said above, that's because pitchers don't have any control of what happens when the ball is put in play. Bad bounces happen. Some defenses are better than others. What pitchers can control is walking and striking out hitters. That is what separates Clemens and Halladay from the rest of the mediocre pitchers.

Barry Bonds career BABIP: .285

Travis Fryman career BABIP: .313

Now, as a lifelong Tigers fan, Travis Fryman was one of my favorite players growing up. But he ain't Barry Bonds. Yet playing 13 seasons and accumulating over 7200 at-bats, Fryman's BABIP is significantly higher than that of the best hitter in baseball history. Why was Barry Bonds so much better? Again, he struck out less and he drew a ton more walks (as well as hitting for incredible power... more on that in a future post).

BABIP can also be used in the context of an individual player. If you want to find out if a particular player is performing at a higher/lower level than usual or just getting lucky/unlucky, compare their BABIP in the current season to their career average. This can also be used to project whether a player will have a "bounce back" year. We'll check out some examples of this in a future post.