Curveball and Slider Pitchers and the DL

Recently, I posted my 2012 starting pitcher DL projections. In the projections, I used games started, age, and injury history to predict the percentage chance a pitcher will end up on the DL. Today, I am going to give an initial stab at how throwing a large number of curveballs and sliders affects a pitcher’s DL chances.

I started by looking at the season after the season in which a pitcher threw over 120 innings. Normally, 39% of these pitchers will end up on the DL. The percentage increases even more if the pitcher threw a large number of sliders or curveballs.

I wanted to look at extreme slider pitchers. For the cutoff, I used pitchers who threw sliders over 30% of the time. For this list, we found 43 pitcher seasons (around four pitchers per year). The list includes such names as Francisco Liriano, Hiroki Kuroda and Ervin Santana.

The list is not huge. Most starters limit the number of breaking balls they throw. On the other, of the qualified relievers in the league, around 14 pitchers per year make the 30% threshold in one of the breaking ball categories. The problem right now with looking at relievers is that we haven’t established a baseline DL percentage. For now, I will have to work with the limited number of starters. Of these pitchers, over 46% of them ended up on the DL in the next season. While that isn’t a huge jump, it does show some of the extra stress that throwing sliders puts on a pitcher’s arm. To get an idea of pitchers who threw a large number of sliders, here are the top 10 slider-throwing starting pitchers from 2011.

Rank Name SL%
1 Ervin Santana 38.4%
2 Bud Norris 36.2%
3 Edwin Jackson 33.7%
4 Madison Bumgarner 32.4%
5 Michael Pineda 31.5%
6 Ryan Dempster 31.1%
7 Francisco Liriano 28.8%
8 Bruce Chen 28.7%
9 Felipe Paulino 28.3%
10 Alexi Ogando 27.7%

For curveballs, I have to move the percentage minimum down even lower (to 25%) to get a decent number of pitchers. Twenty-seven pitcher seasons make that threshold, with such names as A.J. Burnett, Josh Beckett and John Lackey populating the list. Of these starter seasons, 51% of the pitchers ended up on the DL the next season. For reference, here are the top 10 curveball-throwing starters from the 2011 season:

Rank Name CB%
1 Wandy Rodriguez 37.2%
2 A.J. Burnett 33.1%
3 Erik Bedard 31.2%
4 Gio Gonzalez 27.8%
5 Jeff Niemann 23.7%
6 Jonathon Niese 22.9%
7 Brett Myers 22.7%
8 Ivan Nova 22.4%
9 Philip Humber 21.7%
10 James Shields 21.0%

These pitchers have some added risk for missing time in the season. The risk must be weighed with the pitcher’s quality and age to determine their value. If you are looking at two pitchers that have similar projected numbers, look to pick up the pitcher who throws fewer sliders or curveballs.

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Jeff writes for FanGraphs, The Hardball Times and Royals Review, as well as his own website, Baseball Heat Maps with his brother Darrell. In tandem with Bill Petti, he won the 2013 SABR Analytics Research Award for Contemporary Analysis. Follow him on Twitter @jeffwzimmerman.

15 Responses to “Curveball and Slider Pitchers and the DL”

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  1. byron says:

    Not a statistician myself, but is there a way to control this data for age?

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    • Jeff Zimmerman says:

      I did a bit, but I was limited on the sample size even more. Their was a gap with the sliders throws and not with curveballs.

      The more I look at the data, the more I need to get a baseline with RP and then look at them.

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  2. Robert says:

    I thought that there is some question with Bumgarner as to whether he throws a slider or a cutter.

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  3. Dave says:

    Pineda, Santana, and Dempster scare me a bit, especially with Pineda’s velocity issues (could be related to slider use but doubtful since it was his only his first semi-full season). Bedard will get injured like always, Burnett’s on the DL until June or so, and I don’t think Norris is in danger just yet. Here’s where I have them rated:

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  4. hifilofi says:

    Bumgarner really stands out to me (not only because he’s everyone’s target on draft day) because he’s the 5th least likely to hit the DL per your calculation but throws the 4th most sliders. Perhaps a good case study after the season to see how healthy he holds up.

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    • Dave says:

      I don’t think he DOES throw the 4th most sliders though… I think it’s only like 20% sliders and 12.5% cutters or something… but FanGraphs incorrectly defines them all as sliders (it’s hard to differentiate between some pitches) Either way I don’t think he’s in danger of missing time in 2012

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  5. fang graphs says:

    also critical here would be some indicator of time on the DL (maybe hard to normalize?), or whether these DL stints were arm/shoulder injuries

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  6. BP says:

    Nice article — is there a way to compare to just total risk of pitchers hitting the DL. I want to say maybe 30% of pitchers hit the DL anyway so we’d want to look at lift over that amount no?

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  7. bashfactory says:

    I’m fascinated by predicting pitcher injuries but frustrated because a trip to the DL could mean so many different things. It could mean three missed starts or thirty missed starts. Have you done any work looking at which pitchers are more likely to suffer severe injuries as opposed to simply ending up on the DL as some time or another?

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    • Jeff Zimmerman says:

      I can/have, but the sample size just gets so small with SP. I try to work with samples of at least 20. I am just finding I need to get some baseline data for RP.

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  8. wildbill1221 says:

    The article asks some good questions and begins to get at the answers. However, don’t breaking pitches primarily put extra stress on the elbow? IF so perhaps only elbow injuries should be considered. Furthermore, breaking pitches may not be the cause of an injury, but rather an effect. If a shoulder injury has knocked a few miles per hour off your fastball then perhaps you increase your breaking ball percentage to compensate. This can lead to cascading injuries. Of course, if I am wrong about physiology and breaking ball put extra stress on more than just the elbow then you can just ignore this comment.

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  9. Commodore says:

    Jeff – I’d like to know what the results are for the pitchers that hit this threshhold but don’t get injured. Then I’d like to see the results against league average and the pitchers that don’t make the list. Essentially, without knowing the REWARD half of this well demonstrated RISK, it’s hard to put any value on the information other than potential DL time. To impact my draft and roster management strategies, we’d need to see both cost and benefit. I hope you have time to build on the insights you’ve teased us with. Regards.

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