Innings Count Not the Answer for Young Pitchers

This year it’s Joba Chamberlain. Other years it was David Price, Mark Prior, Cole Hamels, and any other high-ceiling starting pitcher under age 25 making the jump from the minors or returning from injury. The innings count. That imaginary line in the sand baseball people draw that’s supposed to define how a pitcher builds long-term arm strength to prevent future injuries and develop the stamina to pitch a full MLB season.

Relying on innings count is the pitching version of using BA instead of OBP or OPS, it’s a misguided stat that obstructs too many details for teams to make crucial decisions based on it. Teams rely on innings count to monitor the progress of young pitchers, in hopes of protecting an asset over a long period and mitigating the risk of an arm injury. Many other factors contribute to the risk of injury – mechanics, freak events, types of pitches thrown, weather, etc – however, workload is something that teams can directly control. Some preliminary research shows that young pitchers whose innings pitched jumps a certain level year over year early in their career are more prone to suffer arm injuries or a drop off in performance stemming from lack of velocity. Case in point, a star pitcher from each World Series the past few years has suffered a decline or injury in subsequent seasons, which may or may not be attributed to the tremendous additional workload of carrying a team through the postseason – Cole Hamels, Josh Beckett, Justin Verlander and Chris Carpenter, the entire White Sox starting staff.

While it’s intuitive that this would happen, many examples to the contrary exist, calling for a deeper investigation. Using Joba Chamberlain as an example, in some games he has struggled with control throwing upwards of 100 pitches in 4 innings, while in others he has dominated finishing 8 innings with less pitches. The macro view of innings count treats the former as half as stressful as the latter, while in reality Joba incurred an equal amount of work, measured by pitches thrown, in each game, and arguably incurred more “stress” in the 4 inning start as he likely labored, threw more pitches under duress, overthrew, and threw more consecutive pitches without rest. Further, teams use pitch count as the barometer at a micro level, then revert to innings pitch at a macro level to measure season and year over year workload. However, from the Chamberlain example we see the two do not correlate, and provides further evidence that a straight IP count is not an accurate barometer.

To accurately control for workload requires further analysis. Perhaps baseball’s inner circle has access to a more advanced statistic that the public does not use. It should start by linking the micro measurement criteria to the macro criteria – mainly pitch count. This simple change should alleviate many of the inaccuracies and biases in using a straight IP. Delving further, teams want to manage duress, more than straight workload. This calls for incorporating pitches/IP and pitches/batter as a proxy to measure how hard the pitcher works during each segment of work (one inning). Other factors such as pitches thrown from the stretch and even some measure that incorporates the game situation and pitch selection will impact the stress load for a pitcher. Pitching with runners on base in a close game, deep into counts, may cause pitchers to squeeze the ball tighter or overthrow, while pitching with a 5-run lead allows a pitcher to throw free and easy, incurring less stress.

First we have to find an accurate way to measure capture these into a statistic, then perform a backwards analysis on a sample of pitchers that suffered injuries and those that did not using these additional criteria would help shed light on the situation. The point is for a stat that has such a direct impact on the game and that so many people rely on, its garnered an disproportionately low amount of research and scrutiny.

Hopefully, more to come in this column after further review.


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