A look back at a classic study of pitcher injuries.
While looking toward the future with our comprehensive slate of current content, we'd also like to recognize our rich past by drawing upon our extensive (and mostly free) online archive of work dating back to 1997. In an effort to highlight the best of what's gone before, we'll be bringing you a weekly blast from BP's past, introducing or re-introducing you to some of the most informative and entertaining authors who have passed through our virtual halls. If you have fond recollections of a BP piece that you'd like to nominate for re-exposure to a wider audience, send us your suggestion.
Though we still have a long way to go, we have made some progress in preventing pitcher injuries. We may have more manageable workloads to thank for that, and one of the most influential articles concerning how to handle hurlers is the one reproduced below, which was originally published on February 26, 2003.
What are the real mechanical precursors of pitcher injury? And what is the real lesson of Mark Prior's injury history?
Pitching mechanics are a bit like long-snappers in football, in the sense that we hear about them only when something goes horribly wrong. Mechanics rarely enter the discussion until a pitcher gets hurt, but when an ace succumbs to injury, the village folk grab their torches and pitchforks to go on the hunt for blame.
Experience has taught me that there is rarely an isolated cause for a pitcher's injury, with confounding variables that include mechanics, conditioning, workloads, genetics, and plain old luck. The pitching delivery is a high-performance machine, with a multitude of moving parts that must work efficiently in concert for the system to perform at peak levels, and any weak link in the system can lead to a breakdown.
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Chipper's forecasting namesake meets its maker, and it doesn't like his chances.
The Team Injury Projections are here, driven by our brand new injury forecasting system, the Comprehensive Health Index [of] Pitchers [and] Players [with] Evaluative Results—or, more succinctly, CHIPPER. Thanks to work by Colin Wyers and Dan Turkenkopf and a database loaded with injuries dating back to the 2002 season—that's nearly 4,600 players and well over 400,000 days lost to injury—we now have a system that produces injury-risk assessments to three different degrees. CHIPPER projects ratings for players based on their injury history—these ratings measure the probability of a player missing one or more games, 15 or more games, or 30 or more games. CHIPPER will have additional features added to it throughout the spring and early season that will enhance the accuracy of our injury coverage.
These ratings are also available in the Player Forecast Manager (pfm.baseballprospectus.com), where they'll be sortable by league or position—you won’t have to wait for us to finish writing this series in order to see the health ratings for all of the players.
An in-depth discussion about mechanics with the motion analysis coordinator and coach of the National Pitching Association.
Pitching is both an art and a science, and from youth leagues to the big leagues, so is the challenge of keeping pitchers healthy. The National Pitching Association (NPA) is on the cutting edge of research and instruction on all three fronts, and many of their concepts are shared in their forthcoming book, Arm Action, Arm Path, and the Perfect Pitch: a Science-Based Guide to Pitching Health and Performance. David talked to the NPA's motion analysis coordinator and coach, Doug Thorburn.
One of the glaring weaknesses in the injury analysis game is the lack of data. As the injury database is built and populated, we are left with spotty research and anecdotal knowledge, especially when it comes to the crossroads of sports medicine and pitcher workloads. Adding to the problem is the lack of data for both minor league and college pitching. Since pitching is pitching, opponents of workload limitations often bring this up.
In one of the first systematic studies of early pitching workload, Lee Sinins, creator of the Sabermetric Baseball Encyclopedia, studied 135 pitchers who threw 175 innings or more before the age of 22.
In one of the first systematic studies of early pitching workload, Lee Sinins, creator of the Sabermetric Baseball Encyclopedia, studied 135 pitchers who threw 175 innings or more before the age of 22. Age 22 is equivalent to the age-point found in Nate Silver's study on pitcher injury and age--the Injury Nexus--but was selected by Lee prior to the publication of Nate's study. Lee selected the pitchers from The Sporting News 1997 Baseball Register, giving us a distant enough perspective on many of the pitchers and allowing objective analysis on the possible effects of heavy workloads at such a young age. Unfortunately, innings thrown in winter leagues or in spring training could not be counted in this study as the data were not available. Innings were not adjusted for level and the totals are a sum for all levels in a season.
There were a few basic theories being tested in this study. First, the injury nexus would be tested. Despite the strong correlations between age and injury found by Nate Silver, real world numbers should match up closely. Second, while somewhat arbitrary, the 175-inning threshold seems to be a point where fatigue sets in for almost all pitchers. Young pitchers usually have not reached this threshold in their careers and the first test of this level often results in injury, massive failure, or a survivor effect.
The second most frequent question I get after "What the [bleep] is wrong with Nick Johnson?" is "How do you do what you do?" My friend Robert Herzog called me on my radio show last year and really grilled me. He's a friend now, but it was really an annoying question. At the time, my answer was "lots of phone calls and a lot of perseverance." True, yes, but not really the key to it.
Becoming a baseball injury analyst was something of a wonderful accident of luck and timing. Under The Knife started as my answer to another injury analyst who gave incorrect information and answered a question with, "What do you expect for a hundred bucks?" I'd had just enough coffee in me that day to think that I could do better.
It took four years of working as a student athletic trainer on all sports, including baseball. It took medical training. It took the creativity to diagnose something from afar. It's at times like a giant puzzle; I get enough pieces to put things together, but I don't have the box cover to go off of and there are always pieces missing.
Pitching is an unnatural act that invites injury. The stress it places on the
bones of the shoulder, arm, and back is immense. The strain it places on the 36
muscles that attach to the humerus, clavicle, and scapula is remarkable. It is
widely accepted by sports medicine practitioners that every pitch causes at
least some amount of damage to the system.
It seems fair to say that the study of pitcher injuries is an important part of
sabermetric analysis. The statistical evidence available to test theories about
pitcher injuries, however, is often missing. While there are databases that
contain every recorded statistic from the days of Al
Spalding and beyond, and others that document every play of every game
in the past 30 years, a comprehensive database of player injury history simply
However, between a careful analysis of what data is available, the creative use
of proxy variables in estimating injuries throughout time, and the application
of some principles of sports medicine, we are at least in a position to make
some educated guesses about the nature of pitcher injuries. Our particular
focus in this article will be the progression of pitcher injury rates by age.