The Rangers and Gap


Part of the reason I do not author much material here at Shutdown Inning is I am terrible at coming up with ideas. Apathy is also part of the equation, but I guess if one wants to be critical of me, denigrate my lack of creativity. If you follow me on Twitter for some strange reason, you might have noticed I tweet many articles authored by writers at Fangraphs and Baseball Prospectus. I read both websites religiously, but also rely on both websites for ideas because of my before mentioned lack of creative juices. While both websites are excellent sources of baseball enlightenment, the genesis for this article came from Mind the Gap, a chapter in the 2015 Hardball Times Baseball Annual written by Matthew Carruth. If you expected some evolutionary research in the nascent stages, I apologize.

Anyways, I highly recommend purchasing the book and reading the article if you are able to. I will not delve into all of what Carruth discusses, but a brief summary is measuring the importance of pitcher deception by using a statistic Carruth appropriately refers to as Gap, the difference between zone swing percentage (zSw%) and outside the zone swing percentage (oSw%). Ideally, the pitcher desires fewer swings at balls in the zone, and more swings at pitches outside the zone. Making contact with a pitch outside the zone is of course more arduous for the hitter. If a hitter happens to make contact with a pitch in the zone, he is far more likely to do damage than making contact with a pitch outside the zone. Deception can be achieved through a variety of different ways including a consistent release point, or something Marcus Stroman excels at, late movement. The smaller the Gap percentage, the more filthy the pitcher has been. Carruth displayed the ten best and ten worst pitchers from 2010-2014 in regards to Gap in his article, which I cannot link to. Instead, I have constructed the elaborate tables myself for your enjoyment, and to give you the reader an idea of who has stood out, and who has fared poorly since 2010. My graphs only include the top five and bottom five due to there not being much difference between numbers six and ten, and there are not any Rangers listed anyways. Without further ado, here is the top five.

Pitcher Sample zSw oSw Gap
Doug Fister 14001 57.8% 30.8% 27.0%
Chris Sale 8877 59.9% 32.5% 27.4%
Jose Fernandez 3328 60.2% 31.6% 28.6%
Alex Cobb 7693 61.0% 31.0% 30.0%
Andy Pettitte 5943 61.9% 31.6% 30.3%


I’d say the top five are all pretty decent pitchers, and have been rather successful in the big leagues. The next five on the list were Masahiro Tanaka, Chris Capuano, Mat Latos, T.J. House, and Roy Halladay. Here are the bottom five.

Pitcher Sample zSw oSw Gap
Aaron Laffey 1971 67.9% 22.5% 45.5%
Chien-Ming Wang 1620 66.7% 22.2% 44.5%
Kevin Gausman 2349 70.7% 26.2% 44.5%
Alex White 2506 70.0% 26.8% 43.3%
Rubby De La Rosa 2639 68.1% 25.2% 43.0%


The next five worst were Brian Bannister, Jonathan Pettibone, Yordano Ventura, Mike Pelfrey, and Robbie Erlin. The samples of pitches are obviously higher among the pitchers at top of the list, but that has to do with some survivor bias. Gap does not have a strong correlation to overall pitcher success, but it does help to be more deceptive. As Ventura and Gausman have proven, you can still have some success despite the higher Gap, but the chance of succeeding becomes more difficult even though the stat is not that predictive. As the graph indicates, the pitchers in the top ten have certainly been formidable.

You might have forgotten by now, but this website is a Texas Rangers blog. Since you have continued reading this riveting piece for over 500 words, and are probably a Rangers enthusiast concerned about the 2015 starting rotation, you are probably curious as to what some of the Rangers starting pitcher’s Gap was for 2014. Well, I will no longer leave you in suspense. I limited the sample to no less than 250 pitches thrown in 2014, and only pitches thrown as a starting pitcher. I used the fantastic website Stat Corner for my research.

Pitcher Sample zSw oSw Gap
Yu Darvish 2314 60.4% 29.7% 30.7%
Martin Perez 777 61.5% 29.5% 32.0%
Robbie Ross 1069 62.6% 30.0% 32.6%
Derek Holland 523 68.5% 35.8% 32.7%
Colby Lewis 2802 62.3% 28.7% 33.6%
Scott Baker 607 67.4% 32.6% 34.8%
Tanner Scheppers 346 60.9% 26.1% 34.8%
Lisaverto Bonilla 257 61.1% 23.5% 37.6%
Miles Mikolas 931 66.1% 28.2% 37.9%
Nick Tepesch 2014 66.1% 27.3% 38.8%
Nick Martinez 2188 62.3% 23.1% 39.2%
Joe Saunders 782 66.4% 24.7% 41.7%
Matt Harrison 343 67.4% 23.0% 44.4%


Seeing the top two names on the list makes one weep. Long known for his deception, Darvish healthy is one of the elite pitchers in baseball. However, he will miss all of 2015 due to Tommy John surgery. Perez had TJS last May, and could return by the All-Star break. Despite his numbers, Ross induced swings out of the zone at a palatable level, even more so than Darvish. Ross did not receive much help from his catchers as his zTkB% (Balls taken which were thrown in the strike zone) was one of the highest in baseball, and could have experienced some batted ball misfortune. He will try to right the ship this year in Boston. Holland utilized a strategy of throwing his slider out of the zone more often after he returned from injury, and induced more whiffs in the process. Bonilla is interesting in that he had a higher zTkB% than Ross did, albeit in a smaller sample. The repertoire seems to be more suited for the bullpen though. The bottom four of the list is littered with pitchers who did not have very productive 2014s, and yielded poor Gaps.

You may be curious as to how a few other pitchers who are now members of the Rangers organization, but pitched elsewhere in 2014, fared in Gap last season. Well, here is your answer courtesy again of Stat Corner.

Pitcher Sample zSw oSw Gap
Yovani Gallardo 3216 62.3% 24.3% 38.0%
Ross Detwiler 1036 70.7% 30.9% 39.8%
Anthony Ranaudo 635 67.8% 19.9% 47.9%


Eeeek! Gallardo had made a concerted effort to take advantage of an astute framer in Milwaukee by targeting the lower part of the strike zone, and to induce more ground balls when the hitter did make contact. The strategy has worked so far, but Gallardo’s strike out rate has also decreased in the process. Dave Cameron wrote a piece after Texas acquired him that Gallardo might begin to elevate his fast ball more in an attempt to induce more whiffs, which will be key for him to try to fight off the NL to AL penalty in ’15. Detwiler’s numbers in ’14 were yielded as a reliever, but his Gap was actually worse in 2013 as a starter, producing a 41.2% Gap in a similar sample. Ranaudo was awful in his cup of coffee in ’14, and his numbers prove that. Minimum 500 pitches, his 19.9 oSw% was the lowest among all starters in the American League. While it was produced in a small sample, one could say Ranaudo was one of the least deceptive pitchers in baseball. Jeff Sullivan authored this piece shortly after the Rangers acquired Ranaudo for Ross. The article discusses how Ross had many balls thrown in the strike zone called balls due primarily to poor framing. While I was mainly optimistic and supportive of the Ross for Ranaudo trade initially, further research, especially this quickly stabilizing number (Look how many Rangers are at the bottom of this list) created by Jonathan Judge at The Hardball Times, is kinda making me rethink my initial thought. Fangraphs lead prospect writer Kiley McDaniel also thinks a relief role is more likely for Ranaudo.

I have written previously about how important Carlos Corporan and his framing are to both Gallardo and the Rangers chances of success in 2015. With Darvish out for all of ’15, and Perez not due back to after the break, the Rangers rotation is currently projected by Steamer to yield 8.6 fWAR, 9.8 including the bullpen, respectively. Only the Orioles pitchers project to generate less fWAR in the American League. As mentioned above, Gap is not exactly predictive, and does have a weak connection to pitcher success, but as Carruth writes, the Gap metric is useful as a “numerical bridge to statements like “keeping a hitter off balance, or confused, or guessing.”” With Darvish gone, the Rangers do not appear to have much of that currently in the rotation based on recent past performance, unless something changes, which is not impossible. If the pitchers continue to produce similar Gaps, Corporan’s dexterity becomes even more vital, and he then sort of serves as the Rangers Gap insurance (Car insurance employees will love that joke). Is the Gap the end all, be all? No, but the metric is a fun stat to use, and gauge performance, much like the shutdown/meltdown statistic.


“Mind the Gap.” The Hardball Times Baseball Annual 2015. Fangraphs and The Hardball Times, 2014. 399. Print.

Dustin Dietz
Dustin graduated from the University of North Texas with a degree in Radio/TV/Film, and a minor in history. He will often write about pitching mechanics and analytical baseball stuff. You will more than likely disagree with the majority of what he writes or says. In his spare time, Dustin time travels and plays at a replacement level in slow pitch softball leagues.

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