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Better Know A Metric: BABIP

Befuddled About BABIP? I'll Paraphrase!

"See?  I told you you'd like hitting more liners."
"See? I told you you'd like hitting more liners."
Frank Victores-USA TODAY Sports

It's time we delve deeper into Red Reporter's Better Know A Metric series and explore the wonderful world of Batting Average on Balls In Play, or BABIP, as it's a pretty basic - yet important - way to give some perspective to the numbers posted by both batters and pitchers during the course of play. Like most statistics, it's informative, yet not perfect, and while it's not exactly a leaderboard stat, it's a very good underlying measure that can help provide the "why" and "how" answers to many of the counting stats you've come to trust over the years.

While BABIP can be used as an effective complimentary analytic tool for looking at both hitters and pitchers, I'm going to focus on how it relates to hitters for the time being. If you take out the trash and make sure your bed is made before you go to school this week, I'll consider explaining it from a pitching perspective some other time, though.

- What is BABIP?



Before we go any farther, I must inform you that each and every time I hear or read "BABIP," this pops in my head, I do a little shimmy, and my whole day brightens up. Also, if you laugh every time you read the word balls, you're going to give yourself a hernia reading this post.

Unlike FIP, WAR, or wRC+, BABIP's definition is about as straightforward as it can be. Quite literally, it's batting average on balls in play, meaning that it's a ratio of how frequently balls that come off a bat into the field of play result in base hits. Strikeouts aren't included because, of course, it's an out that never saw the batter hit the ball into the field of play, and likewise, home runs are thrown out because they leave the field of play entirely.

In essence, it's a built in way to keep track of how often players get hits when the defense has an opportunity to prevent that from happening and, conversely, how often pitchers allow hits when their defense has a chance to get them an out. Without trying to complicate things too much, let's just imagine that if a player hits a home run, it's because they hit a ball so well that there was no outside influence capable of keeping it from being a honked donker. (We'll also ignore small-park issues, wind, and how other potentially mitigating factors can alter BABIP for now.) That particular outcome is something that should rightfully impact a players batting average, slugging, on base percentage, and other statistical categories because it's a rightfully earned accomplishment. Right? Right.

If doinkstomping chuckwagons is the ideal outcome for every swing, anything less than that - even sharply hit liners to the OF gaps - is therefore both less than ideal, and ultimately capable of being stopped from being a hit by either a speedy OF, a well-scouted defensive shift, or the baserunner being so slow he can't beat a throw (to some extent). Piles, mountains, scores, and gaggles of evidence accumulated over the years has shown that when all types of pitching, hitting, defending, and baserunning are factored in, league-wide BABIP usually sits right around .300. That means that roughly 30% of the time a hitter makes contact sending a ball into the field of play, they get hits, and some 70% of the time the defense gets the would-be baserunner out before they get to 1B.

- Semi-Useful BABIP Context

There are a few tenets of BABIP belief that, barring minor exceptions, generally hold up under scrutiny. Hard hit balls generally go for more hits than softly hit balls, for instance, and the longer that balls stay in the air, the more likelihood they'll be caught for outs. As a general rule, fly balls result in more outs than ground balls, and ground balls result in more outs than line drives, which makes pretty good sense.

If you hit the ball hard and hit lots of line drives like, say, Joey Votto, it shouldn't come as a surprise to see a sustained BABIP above the generally accepted .300 level. Votto's never had a BABIP lower than .328, and his career mark sits at a robust .359. Last year, Votto hit line drives 27.2% of the time, which was good for 7th best in baseball, and if you look closely, nobody in the Top 10 in Line Drive percentage had a BABIP lower than .325. On the other hand, if you take a look at the 10 players with the worst Line Drive percentage in the league last year, you'll find that only Hunter Pence managed to have a BABIP above .300, which is purely a product of his goofiness. Similarly, if you take a look at the league leaders in Fly Ball percentage, you'll not only find a who's who of sluggers in the league, but you'll also see mostly low BABIPs, too (except for a rather freakishly high .336 from the Orioles' Chris Davis, who just had a monster year).

It's also common to find above average sustained BABIP levels from speedy, high-contact hitters, especially early in their careers when their legs can help them beat out throws for infield singles. Ichiro Suzuki, for instance, routinely had BABIP levels above .350 during the early portion of his MLB career, and Juan Pierre had a BABIP of roughly .320 through his first 8 seasons in the league. Luis Castillo sported BABIPs of .363 and .395 through his first two full seasons, and though those do seem high even for a player who fits this profile, he still finished his career with a .329 mark.

On the flip side, it's not surprising to find that lumbering, high Fly Ball percentage guys like Carlos Quentin (career .258), Carlos Lee (.284 career, under .300 11 of 14 career seasons), and Adam Dunn (.240, .246, and .266 the last three seasons) routinely have a lower percentage of balls in play end up as hits. They have fly ball swings, and when they hit it well, it's gone. If they don't, it's more likely than not a fly out to the outfield, and when they hit a ball on the ground, well, the defense has an extra second and a half to throw them out at 1B.

Looking solely at a player's BABIP doesn't reveal a ton, and it certainly won't tell you much without exploring things deeper, but it can serve as a pretty solid indicator when someone's statistics seem to look like an outlier. Players' BABIP generally matches their hitting profile, and it's that profile that should serve as the benchmark for any comparison. If young Ichiro had a season with a .305 BABIP, it would be uncharacteristically low for him despite being slightly above league average, and I'd bet you that if Carlos Quentin ever managed a 600 PA season with a .295 BABIP, he'd set a career high for WAR and be an MVP candidate.

- What's This Mean for the Reds?

BABIP, more than anything, is all about setting realistic expectations. If there's a free agent out there coming off a season that saw them sport a BABIP 40 points higher than their career mark, any GM would be wise to curb their expectations (and any potential contract offerings) accordingly, since it's likely that the previous season was the exception more than the rule. Omar Infante, who just signed a 4 year contract with the Royals, is coming off a year that saw him post the highest WAR of his career (3.1), but it also saw him post a .333 BABIP, some 25 points higher than his career mark before 2013 started. Everybody wave at Dayton Moore!

If you're a Reds fan, you're hoping that Walt Jocketty doesn't feel panicked and overpay via trade for a player coming off a BABIP spike. Colby Rasmus, for example, had a .356 BABIP last year en route to a career high in WAR, SLG, and wRC+ (tied); his career BABIP of .298 suggests that's a bit of an aberration, though, so while trading for Rasmus wouldn't be a terrible idea, trading for him and expecting a 2014 similar to his 2013 would.

You're also hoping to see a bit of positive regression from several key players, as there were barely any Reds who came anywhere close to having what you'd call a career year in the BABIP department in 2013. Brandon Phillips' .281 mark lowered his career mark down to .291, Todd Frazier's fell from a too-high-to-expect .316 in his rookie year to a too-low-to-expect .269 in 2013, and poor Devin Mesoraco's .264, while a career high, still seems woefully low for a guy who hit line drives at a percentage like he did (21.1%).

Probably more than anything, though, you're hoping that a now-in-prime Jay Bruce is maturing into a different hitting profile and that, not luck, was behind his .322 BABIP in 2013. Much like the inconsistency he's been dogged for within seasons, his BABIP has routinely fluctuated wildly during his still young career, too. His 2009, easily his worst season in the big leagues, coincided with a near comically low .221 BABIP, while the best season of his career by rate stats (Paul, that's when you use things as a percentage instead of just counti...y'know, nevermind) saw him sport a .334 rate (2010). Jay's line drive percentage was at a career high level in 2013 (23.9%), up significantly from his 2011 (16.8%), and with that came a 59% rise in doubles (27 to 43) coupled with just a 6.7% drop in HRs (from 32 to 30). That kind of tradeoff fits the profile of a line drive hitting extra-base machine, not just a swing for the fences slugger, and if that's the case, his .322 mark in 2013 may be more indicative of the kind of hitter he's maturing into rather than just a spike over his career .297 mark.


So yeah, BABIP's kind of like the bass player in most bands: really good ones stick out, really bad ones stick out, and most all really good bands have a pretty consistent one. If a player's BABIP stays around their career norm from year to year and they stay healthy enough to play a similar number of games each season, you're probably not going to see much of a change in their overall numbers, and vice versa.

Just remember, BABIP only really tells you about a player when compared to his hitting profile and his career norms. Comparing Brandon Phillips to Josh Willingham is like comparing apples to oranges, and comparing either of them to Joey Votto is like comparing brussel sprouts to passion fruit. (Paul, that's when you look at one player's value stats in compariso...y'know, just nevermind.)