Anyone who reads this site regularly knows that I’m not a giant stathead and don’t have anywhere near the sabermetric knowledge of the USS Mariners and Lookout Landings of the world, nor do I strive to be at that level, so I’m not usually one to write a post focusing on one statistic and its application.  Still, the same incorrect use of BABIP (otherwise known as a hitter’s batting average on balls hit into play) came up three times today– twice in private conversations with regards to fantasy baseball and once in a Geoff Baker blog post– so I wanted to take a quick second to issue a brief explanation of one small aspect of the stat.

BABIP is a great quick reference stat that can help determine if a hitter is lucky/unlucky or good/bad.  There is a degree of interpretation involved though, as there isn’t a baseline BABIP that is normal for everyone.  Different types of players have different baselines, as well as other random anomalies.  That said, instead of saying “Player A’s BABIP is much higher than league average, he’s due for some serious regression!” a better use, at least as I understand it, would be to say “Player A’s BABIP is higher than his career averages, he’s due for some regression!”

Two people told me today that B.J. Upton’s BABIP is high and as bad as he’s been, he’s probably going to get worse.

B.J. Upton’s BABIP this season is .326.  For a lot of guys that might be cause for concern, but not for Upton.  He has a .354 BABIP in over 1800 career at bats.  Upton runs consistently high BABIPs for a variety of factors, his speed one of them.  .326 would be a high BABIP for Jose Lopez, whose career mark sits at .288 (around league average), but for Upton it’s actually a tad bit low, which makes sense given his early season struggles.

Geoff Baker mentioned today of Juan Pierre:

his batting average on balls put in play is a whopping .368 — about 80 points above average. So, his numbers might be due for a tumble.

Same thing.  That number looks ridiculously high compared to someone like Jose Lopez, but how in the world are Jose Lopez and Juan Pierre comparable?

Pierre’s .368 BABIP is indeed high and he is indeed at risk of seeing his performance drop, but comparing .368 to ~.290 looks a lot worse than comparing .368 to his career mark of .329.  A 40 point disagreement is a lot when it comes to something like batting average.

</rant>