I love calculating lesser-known baseball statistics just because. I know what you’re thinking: “Pump the brakes, bro, they’re just numbers.” Point taken. The truth is I never took a single statistics course in school but I know this much: while baseball statistics aren’t solely intended to predict future performance, they can provide a glimpse into developing trends.
There is an advanced baseball statistic called BABIP. It stands for batting average on balls in play. Once a batter puts a ball in play, there are many different outcomes: a ground ball to the left or right, a line drive to left, center, or right field, a fly ball to left, center, or right field, pop up in the infield, the ball could hit a base runner, and so on. Critics of BABIP say it’s unfair to penalize the pitcher when he doesn’t have much control over what happens once the ball is put in play (unless, of course, he actually fields the ball himself).
With that bit of background, I’ll first touch on the BABIP formula and then discuss where, traditionally, pitchers have a distinct BABIP advantage. Lastly, since I’m also a Phillies fan, I’ll put the Phillies relievers under the microscope with regard to their early-season BABIPs and tell you if there’s cause for concern.
First, let’s get geeky. The key variable in the BABIP formula is obviously “balls in play.” Home runs aren’t actually in play so they’re out (no pun intended) and won’t count against the pitcher. Walks don’t count as an official at-bat so they won’t count against the pitcher either. Strikeouts, like home runs, don’t involve a ball in play, but sacrifice flies are technically in play though not an official at-bat. So here’s how to calculate a pitcher’s BABIP:
- Subtract home runs from total hits
- Subtract strikeouts and home runs from the total at bats and add the number of sacrifice flies
- Divide the total from #1 by the total from #2 to get the BABIP
BABIP was once thought to be a random statistic, grounded more in defense and luck than in skill. For example, Pitcher A and Pitcher B are both left handed, both have around a 4.00 ERA, both have modest strikeout percentages, and both field their position the same. Pitcher A has Gold Glove shortstop Jimmy Rollins behind him while Pitcher B has James Rolland, a minor league shortstop call-up with poor range, behind him. Chances are Pitcher A and his BABIP will benefit from having Rollins behind him, whereas Pitcher B may surrender more infield singles because Rolland has worse range, a worse glove, a worse arm or a little of each.
Further studies, though, have refuted BABIP as a random statistic. A study conducted by FanGraphs.com between 1995 and 2008 shows that the home team pitcher has a distinct BABIP advantage.
So what exactly is a good BABIP? Is it below 4.00, like a good ERA for a starting pitcher or below 2.00, like a good ERA for a relief pitcher? Not exactly. A good baseline BABIP is somewhere between .290 and .300. According to FanGraphs.com, through games played on April 11th, Phillies relievers have the second-worst BABIP in baseball (.368) behind the Yankees (.412). I calculated the Phillies’ relievers BABIP myself and got a slightly higher number (.379). Going back to the formula, here’s how I arrived at that number:
- Subtract 3 home runs from 28 hits to get 25
- Subtract 29 strikeouts and 3 home runs from 97 at-bats to get 65
- Add one sacrifice fly to 65
- Divide 25 by 66 to get .3787
I’m still not sure where the discrepancy is but it’s pretty bad either way.
To break that down even further, here’s a table that shows BABIP stats by Phillies’ reliever:
Since the FanGraphs.com study highlighted a BABIP pattern which favored the home team’s pitcher, I took that as a challenge. I wanted to see if the current Phillies’ relievers’ career BABIPs were, in fact, better at home than on the road and here’s what I found:
|2013 BABIP||Career BABIP Home||Career BABIP Away|
* Has pitched in 48 career games
** Has pitched in 20 career games
The fact that Jeremy Horst has a career home BABIP more than one-tenth of a point worse than his career road BABIP, in my opinion, is an aberration due to park factor. In 2011, he pitched the first 12 games of his career at Great American Ballpark in Cincinnati, which, according to ESPN, slightly favored pitchers. He pitched 32 games in Citizens Bank Park in 2012, which, according to ESPN, also slightly favored pitchers. So you would think that his home BABIP would be slightly better than his road BABIP. Keep in mind I did not take home runs into consideration when looking at how Horst was affected by park factor, since BABIP does not factor home runs into its formula. In reality I think Horst’s small sample size has skewed his numbers and, in order to get a more accurate BABIP number, he needs more games under his belt.
Jonathan Papelbon’s higher career home BABIP makes perfect sense to me. He’s a career flyball pitcher (771 fly balls / 1,265 ground balls and fly balls = 60.9%) who pitched in Fenway Park from 2005 – 2011. Fenway Park’s park factor favored the hitter in every year except 2005 and 2009. Flyball pitchers generally have an advantage with regard to BABIP for the same reason I mentioned above. Pitchers who allow more fly balls than others will surrender more home runs as well. But this won’t count against them since they’re not calculated in the BABIP formula. As will be the case with Papelbon and pitchers of his ilk, K% and K/9 are excellent secondary statistics to use to gauge a relief pitcher’s effectiveness. In his career as a reliever, Pap owns a career 30.2 strikeout percentage and 10.92 K/9 rate. Not too shabby.
What does this all mean besides the fact that I had some free time on my hands?
BABIP is a complex baseball statistic that can provide insight into how your favorite player or team is faring in this particular category. As far as the Phillies’ relievers are concerned, while it may be too early to predict future success of the squad based on their BABIP right now, it’s a safe bet that most if not all of them will regress to their career mean by the end of the season.
Where the Phils will be in the standings at that point is anyone’s guess.