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How the Rays Improved BABIP by Fortifying the Infield

Or, Hunting the White Whale of Sabermetrics.


In our most recent Roundtable, I led a discussion on the Rays' recent struggles with BABIP (batting average on balls in play) and in-field flyballs (IFFB%).

The Rays offense was near league worst in both of these categories last season, and the cause could have been attributed to just about anything: the talent of the batters, the defenses faced, the park the Rays played in, or just plain luck.

While it is difficult to pin point an exact reason for the Rays shortcomings, we can investigate as to whether the front office responded with their player acquisitions this off-season.

BABIP has become the white whale of advanced statistics in baseball, but that doesn't make it un-observable. Dan Rosenheck presented research at this year's Sloan Conference that shows how aspects of BABIP can be directly impacted by specific batted ball tendencies and the plate disciplines of batters, which he discussed with Fangraphs yesterday.

According to Rosenheck's research, future BABIP production can be specifically correlated to past performance in Z-Contact% -- the rate a batter makes contact when swinging at a pitch thrown in the strike zone -- and IFFB%. Rosenheck published this observation from the perspective of pitching, but the principles can be applied to the batter as well. In theory, improving performance in both these statistics would give the Rays an opportunity to improve their BABIP as well.

You may be shocked to learn that the Rays were league worst in Z-Contact last season at 84.4%, and had the second worst* IFFB with 12.2%. League average for IFFB was 10.0% in 2012, and Z-Contact rates averaged 87.2%. If the Rays had improvements to make this off-season, it's not hard to identify where.

*The Mariners led the league in IFFB with 12.3%.

Now that we are on the other side of the off-season, it's clear that the Rays made a concerted effort to fortify the infield for 2012, but none of the infield acquisitions caught attention for being offensive upgrades. However, we can compare the key statistics identified by Rosenheck for the previous and new infield players to see if the front office made efforts to improve BABIP-related categories through these signings, which would hopefully give the Rays a little more luck at the plate.

For simplicity's sake, I'll be using stats from 2012, with notes to any career averages as they prove significant. Rosenheck's research provides ample opportunity for regression testing and predictive models, but that's beyond the scope of this article.

Let's take a look at the changes the Rays made around the diamond.

Improving the Infield

First Base PA Z-Contact% IFFB%
Carlos Pena 600 75.5% 16.5%
James Loney 465 93.3% 6.2%

Acknowledging confirmation bias, this is exactly what I was looking for.

When the Rays signed Loney, we knew the first baseman boasted a strong glove, one third the strikeouts of Pena, an inability to hit southpaws, and not a huge fall off for on base percentage. In 2012 the league average wOBA for first baseman was .329, Loney's same mark in 2011 and giving him bounce-back potential for 2013.Diving in closer, we can see another decided advantage.

Loney features contact rates well beyond Pena, inside and out of the strike zone. In 2012, Pena offered at 27% of pitches outside the zone, and made contact half the time. Loney offered at 35% of pitches outside and made contact on 80%. Most of all, both players swing at 67% of pitches inside the zone, but Loney hardly swings and misses.

Add in consideration for his performance with IFFB, a top ten mark for first baseman in 2012, and we can see that Loney should be a strong upgrade for the BABIP-beleaguered Rays.

2nd / UTIL PA Z-Contact% IFFB%
Jeff Keppinger 418 95.6% 11.2%
Kelly Johnson 581 82.5% 9.4%

Kelly Johnson will play the role of utility infield backup in 2013, and will start the year at second base until Wil Myers arrives and Ben Zobrist shifts back to the diamond.

Johnson is the only infielder signed that doesn't boast an improvement in plate discipline at his position. It's worth mentioning that he has previously held contact rates in the high eighties, capping at 93.9% in a half season with the Braves in 2009, but it's probably even more worthwhile to look at the bigger picture. The Loney signing does more to replace Keppinger than Johnson does, and if we are making true comparisons, Johnson is more likely to match Sean Rodriguez's plate appearances from 2012.

Johnson's decline came during his three year tenure in Arizona and Toronto, and he may have bottomed out in 2012 with a 5% spike in ground ball and pop up rates. Johnson also tends to excel in the first half of the season, where he projects to find most of his plate appearances, biding time for Wil Myers. If Johnson can regress to his 2011 levels of a 1.0 GB/FB ratio and 5% IFFB, he joins the list of Rays infielders ready for a rebound season.

The other utility infielder for 2013 will be Ryan Roberts, who the Rays acquired in a mid-season trade with the Diamondbacks last year. Roberts is squarely league average in both peripheral statistics we are investigating, and should provide the Rays with solid depth. He'll be vying for playing time at third base on days the Rays start Evan Longoria at DH or have an opening in the infield.

Short Stop PA Z-Contact% IFFB%
Elliot Johnson 331 84.9% 14.5%
Sean Rodriguez 301 81.8% 17.6%
Yunel Escobar 608 91.7% 4.1%

The day before the Rays acquired Wil Myers, the front office traded for Yunel Escobar, effectively shutting down most trade rumors involving the Rangers and Jurickson Profar. As the story goes, the Rays were still involved in talks with Texas and the Diamonbacks, but Andrew Friedman's pre-emptive move to buy low on Miami's recently acquired short stop -- a player with fantastic potential for a rebound season, and under control through 2015 -- certainly shored up the Rays' BABIP peripherals.

Escobar already boasts a shockingly low IFFB%. In fact, only Derek Jeter scored lower for qualifying short stops in 2012, and his career numbers are not far from this mark. His contact rate is a strong upgrade from the normal suspects that have played short stop for the Rays, and Joe Maddon is even predicting a gold glove season.

Third Base PA Z-Contact% IFFB%
Evan Longoria 312 85.8% 4.6%

All things considered, the X-Factor for the infield in 2013 will certainly be the health of Evan Longoria -- who was only able to log half a season of plate appearances in 2012. As Woodrum showed last December, the Rays roster benefits mightily from Longoria's bat in the lineup, and the same is true in regards to team BABIP factors.

Longoria's career averages well below the league with a 7.1 IFFB%, and it's worth noting that dropped drastically to 4.1% in 2012. In the first half of the season, Longoria even notched a 0.0% in 82 PA's. That's a small sample size, but it's a marked improvement from his issues with pop flies in 2011. His Z-Contact rates were better than the team average at 85%, and he maintained an 88% in the two seasons prior to his injury.

Using Longoria instead of replacement players for half a season can surely trend the Rays offense higher in these peripheral categories.


I'm not claiming to be an expert on every facet of BABIP, I'm just an observer, but it's clear the front office has made dramatic improvements this off season, replacing roughly 2200 plate appearances in the lineup with players that excel in contact rates and and batted ball tendencies.

If Rosenheck's research (and my understanding) proves true, the lack of pop ups and the improve contact rats inside the strike zone should give the Rays an opportunity to climb the ladder on the BABIP leader boards, and improve upon what was one of the best offenses in major league baseball last season.