10 Year Disabled List Trends

With disabled list information available going back 10 years, I have decided to examine some league wide and team trends.

League Trends

To begin with, here are the league values for trips, days and average days lost to the DL over the past 10 years.

Generally the data shows that days lost and trips generally go up to a peak near 2007 to 2009 and then drop down a bit in the last couple of years. The most recent issue of ESPN the Magazine states:

“But industry experts have noticed that the window of lower rates [in the early 2000’s] could mark the peak of performance-enhancing drugs, which are thought to accelerate recovery.”

While the article may suggest that PEDs were behind the spike, I would like to bring forth another cause. The age of the players. Here is a graph of the average age of hitters and pitchers since 2002:

Hitters have, on average, got 0.5 years younger while the average pitcher’s age went up 0.5 years and then dropped 0.7 years. The increase and then drop in days lost may have more to do with younger, less injury prone players in the league than PEDs. To show the point further, here is a graph of the average age of pitchers and hitters over the 10 years versus the days lost to the DL.

While I am dealing with a small sample size, there is a decent correlation (R-squared of 0.51) between average days lost to the DL for pitchers and their average age.

Team Data

Here is the cumulative values for Days and Trips to the DL over the past 10 years.

The main point when looking at the long term trends is how the Chicago White Sox are able to lose fewer than half the number of days as 8 other teams (Colorado, Arizona, Kansas City, Cincinnati, LA Dodgers, Washington, New York Mets and Texas). In the last few years some teams, like the Dodgers, have tried to put a better foot forward in limiting injuries.

Another point is that teams have an expected winning percentage as seen in this discussion at The Book Blog. Some teams under and over perform their expected winning percentage based on the team’s salary over the last 10 years. Some of the teams who under performed, like the Mets and Royals, are at the top of the days lost to the DL. Teams who have out performed their expected winning percentage, like the Cardinals and Twins, are in the bottom half of the list. It takes money to get wins in baseball. If that money is sitting on the bench because of an injury, the team can just expect to win fewer games.

For more recent trends, here is a look at the days lost to the DL over the last 10, 3 and 1 year intervals.

Some teams, like the Royals, Rangers and Cubs, have seen marketed improvements in the last few years. Other teams like the Dodgers, who are supposed to be on the tip of the spear in disable list prevention, are only seeing their numbers get worse.

Finally enough data is available to make some OK conclusions from disabled list data. The time lost to players on the DL peaked a few years ago, but has been heading down because of possible decreases in PED use and/or the declining ages of players in the league. Some teams are beginning to put forth more of an effort into prevent DL trips. The results right now look mixed. Team will never be able to prevent all injuries, but they can aim to prevent as many as possible.

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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.

37 Responses to “10 Year Disabled List Trends”

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  1. siggian says:

    “While the article may suggest that PEDs were behind the spike, I would like to bring forth another cause. The age of the players.”

    The two might be related though. The PEDs could have helped the older players retain their skills and recover faster, which made keeping them worthwhile. Now that PEDs have been banned, the older players are declining a bit faster and taking longer to recover, so replacing them with younger players gains traction.

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  2. ben says:

    I appreciate that Mets colors wer used on all of these graphs

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    • Cory says:

      It seems only fitting. Though the Twins colors might be more appropriate given the subject matter.

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      • jon says:

        the mets injuries the last few years have been on the verge of comical. someone will go in for a broken toe nail, miss two days, then they’ll announce the toe might be broken, and 15 days later the guy is out for the year. Seriously, that’s barely an exaggeration with how ridiculously bad the mets training staff has been at diagnosing injuries.

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      • theDAWG says:

        File under “Alex Cora had to make his own thumb splint like Macgyver using a piece of an old bicycle tire”

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  3. jsp2014 says:

    It may not have a major effect on the numbers, but I think for a given minor-to-moderate injury, a player in 2012 is far more likely to say something to a team doctor than a player in the mid-2000s was. This is especially true in pitchers.

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    • Brad Johnson says:

      yea, what kind of effect do you predict from that? On the one hand you probably increase the number of DL stints. On the other hand, you (hopefully) reduce the duration of injury and/or prevent the injury from getting worse. And you (again hopefully) probably save a few careers here and there, which wouldn’t necessarily show up in this data.

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  4. Detroit Michael says:

    FYI, it seems to me that MLB encouraged teams to place players in the DL during September 2011 so that these types of statistics reflect actual injuries. That might be responsible for much of the slight uptick in 2011 DL trips compared to the prior years.

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  5. J Walter Weatherman says:

    Love the graphs. Small suggestion for the last one though: change the subtitle to “(10, 3 and 1 Year Averages)” so it reads more intuitively, being that the 10 year average is the highest bar.

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  6. adohaj says:

    It took me a while to figure out that CHA meant Chicago “AL”.

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  7. Takeaway says:

    My reaction to the graphs and data was how little things have changed since 2002. I think you are making a case against PEDs having an effect on DL time. The differences seem more like noise than any deeper systemic power at work.

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  8. Mike Green says:

    Where the one-year figures DL vary considerably from the three-year and ten-year averages, I would be inclined to attribute the difference largely to luck. This might be one thing to account for when looking at projecting the Angels, Rays and Royals (negatively) and the Giants, Marlins and Indians (positively).

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  9. Really cool stuff.

    Where did you find all the data?

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  10. SeanP says:

    I just read through that article on Conte and the Dodgers’ injury prevention program. The author notes that “Conte started evaluating individual players through risk-management systems not unlike what a life-insurance actuary uses, plugging in variables such as age, position, service time and past injuries to determine the odds each would hit the DL.”

    So, it’s possible that we’re not seeing the whole picture when we compare the Dodgers’ DL stats with other teams’ DL stats. Their model might work well for identifying possible injury-risks, but that doesn’t help them in Total DL Days because it doesn’t help them prevent injuries. They might look especially bad in the charts if those DL Days come from under-control players rather than free agent signings. Just a thought.

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  11. West says:

    Herm Schneider FTW!

    (he’s the White Sox big fat trainer)

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  12. Jonathan Lindberg says:

    The ‘Average Days Lost To DL’ chart strengthens the argument that batters should be drafted before pitchers in fantasy. Elbow or shoulder issues can tank a pitcher for an entire season. It’s rare that a batter has a knee or ankle injury that puts them out for the season. Usually it’s just a pulled muscle.

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  13. pft says:

    I have noticed that the Red Sox tend to use the DL as a roster management tool in recent years with the phantom DL. This could be a league wide trend.

    In any event, I don’t think the numbers showing an upward trend are statistically significant. p-value?

    PED’s may have prevented some injuries but were responsible for injuries as well (especially tendon injuries). I am not sure PED’s have been eliminated anyways given the hypothesis of Comte that players are using short acting testosterone to avoid detection.

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  14. Bhaakon says:

    Just eyeballing the lists, it looks like dome teams have a systemic advantage on non-dome teams. As a typical needy commenter demanding loads of work and offering to do none, I wonder what the correlations between weather conditions and injury rates are.

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  15. Juancho says:

    The 2011 Royals’ aversion to injuries might be related to their youth; all of the 2012 starting lineup will be under 30. Their mid-’90s injury-prone peak is partly due to their signing lots of broken-down old hacks like Reggie Sanders and Juan Gonzalez, throwing their pitchers’ arms out, and having Mike Sweeney on the roster.

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    • Blue says:

      Yep. I think what we’re seeing is a systemic effect due to age.

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      • Bhaakon says:

        I don’t know there are other things that might be causing this. The influx of new stadiums, with better drainage, less turf, less sharing with NFL teams, and more domes might be having an effect as well. I’d imagine that having fewer games played on a sloppy mess of a grass field or cement with a ratty carpet coating positively impacts injuries in general and position player injuries in particular.

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  16. Chris from Bothell says:

    It’s hard to draw anything conclusive from these unless there’s a reliable way to filter out “real” DL trips from “fake” DL trips. By fake DL trips, I mean taking what would normally be a minor injury that the player would play through, or rest on the bench for, and inflating its severity enough to hide that player on the DL.

    I’m sorry that I don’t have good data to back up the following assertion, but it seems that teams do use the DL a fair amount to gain temporary roster flexibility, rather than healing a truly injured player. I.e. antics like shoving a slumping player onto the DL rather than an extended benching, making room for an extra bullpen arm, or unjamming temporary logjams without releasing a player outright.

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  17. Keystone Heavy says:

    Texas Rangers most trips and total days lost to DL since 2002?

    Damn you Nelson Cruz’s hamstrings! DAMN YOOOOOOOOOUUU!!!!!

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  18. joele says:

    proves to me pitch counts don’t mean a thing as far as protecting pitchers goes. when will the “experts” who freak out about a manager “abusing” a pitcher going over 95 pitches in a start admit what the hard data is telling them — that pitch-count-limited pitchers today are no safer than they were when they regularly went 150 per game and 300 innings in a year?

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  19. Joebrady says:

    “I collected some myself:


    The rest going back to 2002 is owned by Fangraphs.”

    The grey line in the 1, 3, and 10 year averages, for the NYY, shows about 650 days lost. On the link you provide above, the NYY lost about 1,500 days.

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  20. Jim Lahey says:

    I wonder what the pitchers look like as a group of you excluded season ending surgeries. I imagine they have so many days lost more than hitters because guys go on the DL for 18 months just to rebuild arm strength

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