BABIP: From the White House to the Outhouse

Batting Average on Balls In Play (BABIP) burst onto the baseball landscape like a meteor, illuminating life on the diamond in its wake. By measuring the part of the game largely outside the control of the pitcher (and somewhat outside the control of the batter) it appeared to separate skill from luck.

If the Royals' Billy Bulter hits .341 on balls in play in 2012 and Shane Victorino hits .278, might that not suggest that Butler was crazy lucky and Victorino not so much? If we were making predictions about the following year, might we not temper Butler's prediction and enhance Victorino's on the notion that luck will average out?

The answer, it turns out, is: well, maybe. After cuddling up beside BABIP for several years, seamheads started to notice that it had some idiosyncracies. BABIP just likes some guys better than others. Speedsters are particular BABIP sweethearts because they can get on base without hitting the ball hard. Ichiro rocked a .357 BABIP through 2010, but as his speed has waned, he's suffered three sub-.300 BABIPs since.

Worm killers romp with BABIP because ground balls tend to find holes more often than fly balls. That's offset by the fly balls that do make safe landing, which tend to result in extra base hits. Pop-ups are BABIP death and line drives are BABIP medicine, for obvious reason. And batters can control their BABIP to some degree. The aforementioned Ichiro didn't just hit the ball; he often placed it, much to BABIP's delight.

BABIP can start the narrative, but not complete it. Certainly Butler doesn't have foot speed on Victorino, but he launched many more line drives and many fewer pop-ups than Victorino in 2012. That suggested there might be some staying power in those numbers; i.e., there might be some skill involved.

In 2013, Butler did, in fact, maintain an above-average BABIP, losing just 15 points from his 2012 rate. But Victorino, rejuvenated in Boston, "regressed" beyond the mean and up 43 points. Some of that was the result of doubling his line drive rate and much of it was pure serendipity, from a lot of bad in 2012 to a little good in 2013.

It's even more pronounced for pitchers, whose results are affected by the defense behind them, defense that remains largely intact over the course of a season. Rookie of the Year Jose Fernandez allowed a .240 batting average on balls in play, despite fairly pedestrian rates of line drives and pop-ups induced. Fernandez looks highly promising, but BABIP strongly suggests a return to earth in 2014. 

Conversely, all-world starter Justin Verlander played second fiddle to Max Scherzer in Detroit last year, in part because of a high BABIP-allowed (.316). Verlander allowed a lot of line drives, but probably not enough to explain all of BABIP. Likely the Tiger statues at third, short and first contributed to balls getting through. A bounceback may be in order, particularly with Miguel Cabrera moving to first, Prince Fielder and Jhonny Peralta leaving town and Ian Kinsler joining the infield.(Why didn't this matter for Scherzer? A. Luck. B. An 11% higher strikeout rate. Dr. Strangeglove can't flub your strikeout.)

So BABIP is useful, particularly at the extremes, but it isn't quite the revelation originally envisioned. Pure luck is hiding in every facet of the game,but in the nooks and crannies, not out in the open for BABIP to see in its entirety.