Starting Pitcher Disabled List Analysis (2 of 3)
With the general overall numbers available from yesterday’s article, here’s each variable:
Age
I divided the data into several buckets, according to individual pitchers’ ages. Here are the results:
Two numbers jump out. One interesting point is that the pitchers who continue to pitch as they get older have a lower BMI as a group. Another point is that there’s a large jump in Average Disabled List Expectancy (ADLE) from the age 27-to-28 bracket to the 29-to-30 bracket. Obviously, age is playing a part in DL stints.
Body Mass Index – Height and Weight Proportions
Scouts often refer to a player’s build when they talk about injury chances. Using height and weight information available from baseball-databank.org, I divided up the each pitcher’s BMI. Here are the results:
Again, an age bias exists. Younger pitchers have, on average, higher BMIs than older pitchers. Also, the difference in BMI doesn’t appear to be caused by changes in height as height varies by only half an inch. Instead, the main cause of change in BMI from one pitcher to the next is weight — which goes from averaging 185 pounds to 241 pounds. The final interesting trend is that, as BMI increases, there is no real trend in ADLE.
Country of Origin and School Attended
For grins, I wanted to see if there are trends based on a player’s place of birth.
Not much can be drawn from the data. Players from the United States and Latin America make up 95% of the pitchers, and their ADLE figures are almost identical. It’s pretty easy to say that you can’t put much stock into country-of-origin as a factor in DL stays.
But what about players who attended college?
I divided the pitchers into two groups: those who attended college, and those who did not.
It appears that pitchers who went to college have a lower ADLE value — even though, as a group, they are a half-a-year older.
That is all for today. Tomorrow, I will group begin combining all the preceding data to look at deeper trends.
26
“The final interesting trend is that, as BMI increases, there is no real trend in ADLE.”
Tell that to Brad Penny. I’m still pissed at that guy.
So we can finally figure out the most likely player to hit the DL this year…oh wait we already know — Daisuke!
No really though, we could…
Nah, he’s still far behind Joel Zumaya, Ben Sheets and Rich Harden.
There are too many quirks from small sample sizes to draw any sweeping conclusions.
So, are fat pitchers younger because they don’t last as long because they’re unathletic/out of shape or is it a bias against fat pitchers? Based on the ADLE it seems like there’s a bias against heavier pitchers.
Also, since you capped the BMI at 33, did this mean that CC Sabathia wasn’t included in the analysis?
And to be morbid, did you include pitchers who passed away in the analysis?
Once again we have “sabermetric” analysis that attempts to draw a conclusion by comparing point estimates with no information about variance. Is the difference in average days on disabled list (between two age groups) statistically significant? No clue — but the tools to perform such a test are readily available in Excel and elsewhere.
Part One included the statistic that 39% of all pitchers in the sample of 947 wound up on the disabled list. The true value over infinite seasons is probably in the approximate range of 36% to 42%, but let’s assume 39% is accurate. Now, that includes 208 pitcher seasons in the 27-28 range and 165 in the 29-30 range. The margin of error for a 95% confidence interval for chance of DL for a sample size of 208 would be 6.6%; we aren’t told what % of 27-28′s landed on the DL, but if it were 39% for all age brackets we could expect anywhere from 32.4% to 45.6% of 208 pitchers to land on the DL. That alone is enough to account for any observed difference in ADLE between age brackets. Mr. Zimmerman has not demonstrated that any of his observations are anything but random noise — “small sample size” in the usual sabermetric lingo.
“Two numbers jump out. One interesting point is that the pitchers who continue to pitch as they get older have a lower BMI as a group.”
Thats interesting, although not surprising. Heavier pitchers probably have shorter careers than Cliff Lee types, and fewer are pitching at 35 or 36. Not good news for the Red Sox (Beckett) or Yankees (CC)
Lets not forget the phantom DL effect skewing the numbers. Sometimes pitchers are so bad and if they are out of option the only choice is to DL them or DFA them.
I remember the case of Daisuke last year (2nd Dl stint) where Tito sent him to the DL and admitted there was nothing wrong with him that would require him to miss anything mrore than 1 start, but he needed another pitcher from Pawtuckett to make that start, so he DL Daisuke and let him miss 2 starts and sit out 15 days.
The other thing making the DL unreliable is that you have 1 month of the season where pitchers who get hurt do not need to go to the DL because of expanded rosters. Not sure how you get these included without a lot more work..
That said, I like to see such studies since they do a nice job of summarizing what happened, even if only 1 year data makes it difficult to draw many concusions. Over a few years the data will become sufficiently large to draw more meaningful conlclusions.
To complicate the BMI issue: Since recorded height/weight tend to be fixed at the start of a career, a pitcher’s age when he makes the majors will (permanently) affect this stat. The counterintuitive higher BMI for younger pitchers suggests to me that heavier guys make the big leagues faster presumably because they tend to throw harder.
@pft: The Red Sox certainly should worry about Josh Beckett, because he’s only really had the one good year, and that was some time ago. But as far as body type goes, he’s surely a big strong guy, not a big fat guy. I mean, we’ve seen Roger Clemens and David Wells (who of course had long careers).
[...] This post was mentioned on Twitter by ThinkPitching.com, WILL ADUELY. WILL ADUELY said: fangraph Starting Pitcher Disabled List Analysis (2 of 3): With the general overall numbers available from yeste… http://bit.ly/g8Nnjl [...]
[...] Starting Pitcher Disabled List Analysis (2 of 3) | FanGraphs Baseball [...]