After fooling around this morning with some pitch data numbers (PitchF/X), I tweeted the following:
Madison Bumgarner threw 1,250 sliders in 2012, most among all SP.
— Admiral Gaudin (@baycityball) March 9, 2013
Immediately after tweeting, I got into some pretty good discussions with Eno Sarris and Anna (@SFBleacherGirl), among others, on the topic of Bumgarner’s future health and if the slider could be an indicator of a potential future injury. I’m a tad bit skeptical of the vanilla PFX classifications. I’m sure it’s lumping in the occasional cutter into the slider category, though it’s worth noting that Brooks Baseball — another fine PFX resource — has Bugmarner’s slider count at 1,412 sliders. Either way, it’s most likely very accurate to say that Bumgarner throws a bunch of sliders while pitching.
There’s been some decent research done on the slider’s impact on a pitcher’s chances of injury. Sarris’ article in 2011 raises some questions on the pitch. Jeff Zimmerman has also done some interesting work, looking at the pitch and what its effects are on pitchers. While I was combing through some of the data, I decided to do a quick-and-dirty look at the top 10 slider-throwin’ starting pitchers over the period from 2009-2012. I sorted my list on slider percentage (hereby noted as SL%) and then, roughly using other various online resources, did a rough calculation of how many games each pitcher missed with arm issues. (I did not include missed time due to non-arm injuries.)
Here’s what I found:
| Name | Team | P | SL% | Missed Games |
| Ervin Santana | LAA | 12142 | 36.1% | 58 |
| Armando Galarraga | null | 5814 | 34.7% | 3 |
| Bud Norris | HOU | 9595 | 34.6% | 37 |
| Madison Bumgarner | SF | 8266 | 32.0% | 0 |
| Ryan Dempster | CHC | 13019 | 31.5% | 20 |
| Dan Haren | LAA | 13819 | 30.6% | 4 |
| Francisco Liriano | MIN | 10017 | 29.3% | 52 |
| Jeremy Bonderman | null | 2808 | 29.3% | 128 |
| Edwin Jackson | WSH | 13013 | 29.2% | 0 |
Keep in mind that the ‘missed games’ column only covers 2009-2012. Players like Francisco Lirano, who suffered major injuries (Tommy John Surgery) outside of our date range, will not be fully penalized.
As far as I can tell, you could sort this grouping into three subsections: guys who are still pretty good (Bumgarner, Dempster, Jackson); guys who have thrown a crap-ton of innings and despite some degradation in stuff, are still pretty decent (Haren); and guys who are now injured and/or were never that good to begin with (Galarraga, Liriano, Bonderman). I’m not really sure where to stick Bud Norris. He’s somewhat of an injury risk, but his career numbers — 8.8 K/9, 3.3 BB/9, 4.20 FIP — paint him as a talented pitcher with upside.
Bumgarner ranks #3 on our list among all starters in SL%. And while that’s got to count for something — even if I’m not sure how much of something it should count for — Bumgarner does have some positive indicators — he’s never been on the D.L. and even though that logic might sound a little circular, prior injury history is a huge indicator of potential future injury. Though, while he hasn’t been injured, Bumgarner has had some weird velocity-related issues in his past, mostly to do with velocity loss between the minors — where he was ‘throwing in the mid-90s’ — to a period in the majors when he was throwing in the upper-80s. So he’s a little bit different than most pitchers with a clean bill of health.
Bumgarner’s workload is also worth mentioning. In recent history — 1970 onward — Madison Bumgarner ranks #11 among starters (60-percent of all games started) in innings pitched by the age of 22 (534). Matt Cain, by the same age, had already thrown 437 innings; Bert Blyleven had thrown a mind-numbing 1,054.2 innings by his age 22 season. Being so good, at such a young age can be viewed a bunch of different ways. It’s a great indicator of how good Bumgarner has been. It’s also something to worry about.
The Giants have built themselves a lot of credit when it comes to the development (and handling) of their pitchers. I don’t always agree with what the team does, but their recent success in the pitching department is undeniable. Bumgarner, the Giants’ No. 2 starter heading into 2013, is a key piece to the team. If the Giants exercise his options, he’ll be on the team until 2019. So there’s a bunch of reasons — both present and future — to keep Bumgarner’s health in check. Ultimately, it’s hard to say how much Bumgarner’s reliance on the slider will affect him long-term. That’s kind of the thing with pitching, to me at least; it’s hard to know your time might be up. Bumgarner’s health is definitely something to keep an eye on for 2013.
