Pitching at the major league level is not an easy task. One of the more common struggles that pitchers encounter is the challenge of getting opposite handed hitters out. While some types of pitches are more suited to battle such hitters, there are pitchers who just do not have a strong enough arsenal to do so effectively. Most of these pitchers end up in the bullpen, perhaps even rostered with the solitary chore of getting out one or two batters who stand on a particular side of the plate.

There is a relatively small group of pitchers at the major league level who have implemented a strategy of changing their setup or delivery depending on the handedness of the batter in the box. Presumably they feel that doing so lets them target a different part of the strike zone more easily or lets them achieve a different effect on a pitch that is tougher for hitters to handle from a certain side of the dish.

Pitchers naturally will vary release points to throw different types of pitches in their repertoire. Curveballs are not likely to be released in the same location as fastballs, for example. In addition, there is a range of release points within each pitch type over the course of a season. To identify those pitchers who truly exhibit separate release points depending on batter handedness, these variables must be understood.

I looked at each pitcher from the 2012 season, and broke up their pitches by batter handedness and by pitch type as classified in the GameDay files. I then excluded intentional balls, pitch outs any pitch type for a pitcher that was not thrown at least ten times. From the remaining sets, I calculated the mean and the standard deviation of both the horizontal and vertical release points, and then subtracted the mean for LHB from the mean for RHB for each pitch type individually. Since each pitcher has his own variability of release points, I then divided the delta by the maximum of the two batter handedness standard deviations to gauge whether the difference by batter handedness was meaningful for that particular pitcher or whether it fell fairly comfortably within his normal range of release points for that pitch type. Finally I averaged the normalized deltas to get a release point difference for each pitcher.

There are two types of changes that can be observed in looking purely at release point data - setup and delivery. We can consider the two separately.

"The Shifters"

The most common type of difference that is recognizable from this study is one where the pitcher has likely just shifted along the rubber depending on the batter handedness. This type of change is identified by pitchers with a large change in horizontal release point but virtually no associated change in vertical release point. This would suggest that the arm angle is probably very similar, but that the pitcher has just set up in a different location on the mound.

Marc Normandin wrote an article recently at Over the Monster describing the potential benefits of setting up on a part of the rubber to allow your style of pitching to play up, spurred by the changes the Red Sox have made this spring to prospect Allen Webster's positioning on the mound. This certainly could be the underlying reason that a lot of these pitchers shift the way they do.

The following table shows all pitchers who experienced horizontal release point shifts of at least two standard deviations in the 2012 season without a significant difference in vertical release point. The absolute movement in inches along the 24-inch rubber is also included for a better reference of the actual shift.

Pitcher Throws Shift vs RHB Shift vs LHB StdDevs Inches Jason Berken R Toward 1B Toward 3B 6.1 16.3 Jose Contreras R Toward 3B Toward 1B 6.0 18.1 Francisco Liriano L Toward 3B Toward 1B 4.3 11.1 Felipe Paulino R Toward 3B Toward 1B 2.4 5.7 Jose Valdez R Toward 1B Toward 3B 2.2 10.2 Casey Coleman R Toward 3B Toward 1B 2.0 11.2 Alfredo Aceves R Toward 3B Toward 1B 2.0 6.5

Jason Berken had a forgettable 2012 season, straining his hamstring in camp and then getting into only one game with the Orioles before being claimed off waivers by the Cubs in September. He then promptly went 0-3 in four starts down the stretch with a FIP of 6.50. Interestingly, Berken did not utilize this shift in his 2011 season, so the shift appears to have been an attempt to rectify a situation that did not prove fruitful.

Both Jose Contreras and Francisco Liriano are pitchers who have implemented the set up shift over many seasons. Contreras had the largest normalized shift of all pitchers in 2011, and Liriano was spotted doing this very thing at least as far back as 2010. The Twins tinkered with Liriano's positioning at least once when he was in Minnesota, hoping that anchoring him in one location on the rubber could help mitigate his control problems.

Felipe Paulino will attempt to comeback from Tommy John Surgery midway through the 2013 season. Both he and Alfredo Alceves are also notable pitchers who have slid along the rubber depending on the batter for at least the past two seasons.

It appears that it was more common to shift toward the side of the mound closest to the hitter for those who implemented this strategy, regardless of the handedness of the pitcher. In general, there is nothing that I can think of that would be inherently dangerous from an injury perspective about setting up at different locations on the rubber, provided the delivery itself is quite consistent.

It is interesting to note however that Berken, Liriano and Paulino have all undergone Tommy John surgeries, while Contreras hit the DL three separate times last year with elbow problems. Valdez, Coleman and Aceves have all had shoulder-related injuries in the last couple of seasons. This could be just a sign that basically every pitcher gets hurt at least once every couple of seasons, or maybe there is something more to be investigated here.

"The Anglers"

I don't know if these guys like to fish, but we will refer to them as the "anglers" to indicate that they appear to have changed their arm angle depending on which side of the plate the batter was standing.

The difference in arm slot can be identified by a change in both horizontal and in particular vertical release points. As one example, for a RHP a more sidearm delivery would typically show a more negative (toward 3B) horizontal release coupled with a smaller (toward the ground) vertical release.

The list of pitchers who show significant deltas of this type is certainly smaller and the deltas themselves are also smaller, as I would expect. The following table shows those pitchers with vertical release point deltas of at least 1.4 standard deviations. Again the change in inches is included for reference.

Pitcher Throws Change vs RHB Change vs LHB HORZ StdDevs VERT StdDevs HORZ Inches VERT Inches Xavier Cedeno L Over top Sidearm 3.1 2.8 9.7 6.2 Nick Maronde L Sidearm Over top 1.8 1.5 3.3 2.8 Clay Rapada L Sidearm Over top 3.7 1.4 11.6 3.1 Fautino De Los Santos R Sidearm Over top 0.3 1.4 0.5 3.0

Xavier Cedeno, who made 44 appearances in his rookie season in Houston last year, clearly dropped down the most of all pitchers based solely on batter handedness. Cedeno is an interesting story, as after struggles early in his minor league career he was forced to endure the entire 2010 season outside professional baseball. His return has certainly been more successful, and leads me to wonder if he has always used these two release points based on the hitter or whether this strategy has helped to fuel his new found success. Cedeno throws with a more sidearm action when facing same handed hitters, which can be seen quite clearly in the image below that alternates between release points to RHBs and LHBs.

Xavier Cedeno Release Points, RHB vs LHB, 2012 (Source: Texas Leaguers)



Nick Maronde is a promising southpaw in the Angels system, with Eno Sarris recently tabbing him as a darkhorse for some work as the fifth starter in Los Angeles should the injury bug bite the rotation in 2013. John Sickels also included Maronde just inside his Top 150 Prospects List for 2013. Both he and Clay Rapada actually drop down to the side when facing RHB, in contrast to Cedeno.

Former Athletics flamethrower Fautino De Los Santos - who has gone through a chaotic off-season with reported links to Biogenisis - rounds out the list. De Los Santos throws all his pitches from a lower arm slot than most pitchers. In his case he is likely setting up at a slightly different spot on the mound and dropping down a little further against RHBs and ending up releasing the ball at roughly the same horizontal location for all hitters.

In contrast to the pure "shifters", these "anglers" are in my mind playing a riskier game with their arms by altering their arm slot in the manner that they demonstrated in 2012. Injury expert Jeff Zimmerman alludes to the idea that inconsistent release points and injuries are often found together. I have to admit though that at this point I have not investigated a potential link to injury for this specific trait, nor have I read specific research on this topic, so the concern on my part is mostly speculative.

Running a quick medical history on these pitchers, I can see that Cedeno hit the minor league DL in April 2012, Rapada has had a long history of shoulder problems that has cropped back up in camp this spring, and De Los Santos is a Tommy John surgery veteran but has been healthy recently.

Of the three pitchers who altered their arm slots to this extent based on batter handedness in 2011, Alberto Castillo hit the DL with shoulder issues and Rich Hill underwent Tommy John surgery, leaving medical miracle Steve Delabar as the lone pitcher to make it through the year unscathed. Delabar is known for having fractured his elbow while pitching in the minor leagues and the relatively novel rehabilitation approach that has revived his career.

Looking back even further, there were actually no pitchers who altered their arm angles this much based on batter handedness in 2010 nor 2009. In 2008, all three pitchers who met the criteria spent time on the DL that season.

This is hardly proof of anything, of course, merely an indication that many of these pitchers who deviated their releases the most in the last couple of years based on batter handedness have had or currently have injury issues.

So what does this all mean? It provides some of the groundwork for future studies that I plan to pursue in the injury realm related to among other things, release points. To examine the issue further, I would like to look at volatility in release points in general, not specifically grouped by batter handedness. In that endeavor, I will have to first correct the release points as I will no longer be comparing a pitcher against himself within the same game.

For the most part though, this serves purely as information that you will hopefully find interesting about the different ways certain major league pitchers approach hitters from each side of the plate.

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Credit and thanks to Baseball Heat Maps for PITCHf/x data upon which this analysis was based.