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## What the flip is BABIP?

Batting Average on Balls in Play, or BABIP, is a measure of a hitter’s batting average on batted balls that can be fielded (thus are “in play”).  It would include all ground balls, line drives, fly balls (including sacrifice flies), and fielded foul outs.  It does not include at bats where the batter strikes out or hits a home run (the ball is not put “in play” during these at bats).

For example, assume a player has 10 at bats.  Within those ten at bats the player strikes out three times and hits one home run.  That leaves six balls that were batted in play (10 at bats – 3 Ks – 1 HR = 6 balls in play).  Of those six balls in play, two were for hits and four were various outs (ground outs, fly outs, etc.).  In this example, the player’s BABIP would be .333 (2 hits / 6 balls in play).

The official formula for BABIP is:

BABIP = (H – HR) / (AB – K – HR + SF)

## WHAT IS THIS STAT TRYING TO ACCOMPLISH?  WHAT DOES IT TELL ME?

On a very simplistic level, BABIP is a measure of a batter’s luck.  The theory is that a player’s skill contributes significantly to their contact rate (avoiding strike outs) and hitting for power (home runs), but there are other factors (like luck, which is beyond the hitter’s skill or control) that come into play when a ball is batted into play.

When a player hits a hard line drive they may be unlucky and have it hit directly at an opposing fielder.  Or a player may be lucky and hit a soft blooper over the infield.

Figure 1 below shows the BABIP for all hitters with at least 250 ABs for the last five years.  You can see that BABIP hovers consistently around the .300 – .305 mark.

Figure 1 – BABIP for All Hitters with >250 AB

## ARE THERE ANY WEAKNESSES IN BABIP?

I think the main weakness is simply (more…)