Time for a checkup: D-backs pitcher health in 2014

Injuries happen in baseball. That’s a given. Pitchers get hurt more frequently than hitters, which is something that we should also be very familiar with. Injuries test a team’s depth and the next man up has to be able to perform at an adequate level for a team with playoff aspirations. The Diamondbacks are one of those teams and they can’t throw innings and at-bats away if they want to keep pace with the rest of the division.

So, while “building depth” is a great suggestion in a vacuum, is there any way to know how much that depth will be needed once the season comes around? Better yet: can we predict injuries? The answer seems to be yes and no. When it comes to position players, it’s incredibly tough to predict injuries. They can get hurt sliding into a base, hit by a pitch, strain an abdominal on a swing, run into one another in the outfield, etc. Unless the player is aging and has shown a propensity for known injury (think: Eric Chavez), it can be almost impossible to predict.

But what about pitchers? As it turns out, there are a number of factors that lead to frequent pitcher injuries. While no single indicator says a pitcher will get injured, these indicators seem to be predictive of the larger body of MLB hurlers. Think of these indicators for pitchers like an average citizen having a consistently poor diet. Some become obese, some become diabetic (some both) and others skate by seemingly untouched. If you ask your doctor, they can’t guarantee that a consistently poor diet will kill you, but they would certainly advise against it because it increases your likelihood of health problems. These pitching indicators work the same way; they don’t guarantee injury, but they have seemingly led to them across the spectrum of pitchers.

What are the pitching indicators that point to future injury? I’m glad you asked!

• Seasons with a DL trip in the last three seasons
• Games started
• Age
• Heavy breaking ball usage
  • Slider more than 30% of the time
  • Curve more than 25% of the time
• An inability to throw strikes
  • Strike rate less than 60%
  • Zone rate (PITCHf/x) less than 47%

Now, I can’t take any credit for these indicators, as they have been the tireless work of Jeff Zimmerman, one of baseball’s analytical pioneers. Each winter, he’s created odds of DL chances for every starting pitcher in the game (who meets the study’s criteria). Keep in mind, the baseline odds for a pitcher hitting the DL are roughly 39%, so any odds should be compared to that average. For example, John Lackey has a 58.5% chance to hit the DL (19.5% more than average). This should come as no surprise given his age, injury history and erratic nature. Clayton Kershaw, on the other hand, has a 28% of hitting the DL (11% less than average) given his youth, lack of previous injuries and ability to throw strikes. You get the idea.

So without further delay, here are the DL odds for Diamondbacks starters in 2014:

Brandon McCarthy: 51.5%

McCarthy is going into his age-30 season and has hit the DL every year he’s pitched, including the last three. Some of his injuries have been strange flukes while others are common pitcher ailments. He doesn’t trigger any of the other indicators (breaking balls, strike-throwing), but we’d obviously expect Brandon to hit the DL at some point, thanks to his history of injury.

Bronson Arroyo: 40.8%

Arroyo is about to turn 37 and although he hasn’t hit the DL in the last three years, he has logged quite a heavy workload over that span. Of course, Bronson was signed because, up to this point, he’s beaten the odds as a seemingly rare breed: pitchers who can make 30+ starts every year into their late 30’s without injury. Can he continue to beat those odds or is he about to fall back down to earth? The D-backs will hope for the former while the odds above seem to split the difference.

Patrick Corbin: 30%

As we’d expect, Corbin looks to have a great chance of remaining healthy in 2014. He’s young (turns 24 this year) and doesn’t have a problem throwing strikes. He has a clean injury history and while his slider usage is approaching the danger zone, he’s been working on his changeup so he’s not so slider-dependent. Things look good for Corbin.

Trevor Cahill: 33.4%

In 2013, Cahill hit the DL for the first time in the last three years when he went down with a hip contusion and some shoulder soreness. He’s young in that he’ll turn just 26 next season, but he does show some warning signs in the strike-throwing department. If you haven’t already, please Rod’s piece on Trevor Cahill and you’ll see why he’s struggled to throw strikes. Still, the odds of a DL stint seem rather low and it looks like there’s a strong chance Cahill reverts back into a workhorse in 2014.

Wade Miley: 31.6%

Another young pitcher, Miley turns 27 next season and looks likely to remain healthy. He does, however, have some trouble finding the zone regularly, triggering the Zone% indicator. As Rod pointed out just last week, Miley had some struggles in 2013 that look fixable. He’s yet to hit the DL and hopefully he’ll stay off of it again this season.

Overall, the group shakes out about as we’d expect it to: McCarthy will get hurt and someone else might hit the DL along the way, but the rotation as a whole is pretty darn durable. In fact, you’d be hard-pressed to find one with less injury risk than the Diamondbacks’. This is good in the sense that the team won’t likely have to give many innings to guys who aren’t MLB rotation-worthy (Charles Brewer, Zeke Spruill). If anything, options like Randall Delgado and/or Josh Collmenter can get them by in a pinch while Archie Bradley takes his time to develop.

The Diamondbacks can’t afford to throw away innings due to injury, and this case, it looks like they won’t have to.

To read more about how these injury odds are calculated, please see Zimmerman’s methodology (part one, part two). Also, you can see the DL odds for all pitchers in 2014 right here. Enjoy!