The Aftereffects of High Pitch Counts

Jack Flaherty was nothing short of dominant on May 20th against the Phillies, tallying 13 strikeouts while yielding just two hits and a walk over 7.2 innings of one-run ball. In the three outings that followed, Flaherty posted a subpar 4.50 ERA and 4.61 FIP. Now, three games and 16 innings isn’t a particularly alarming sample size, but this comment from June 6th’s game recap nevertheless caught my eye.

I liked pre 120 pitch Jack better

Posted by stlwildcats on Jun 6, 2018 | 11:16 PM

It’s not uncommon to hear similar sentiment expressed anytime a pitcher struggles in the aftermath of a heavy workload like Flaherty’s 120 pitches against Philadelphia. I can’t speak to the injury risk brought about by higher pitch counts, but I was interested in testing how 120+ pitch starts affect future performance on the mound.

Want proof that, even if I can’t get around to replying to them all, I really do read each and every comment you leave for me? I’m writing an entire article about one right now.

To begin, I used Baseball-Reference.com’s invaluable Play Index tool to gather data from every start of at least 120 pitches since 2013. I measured pitching performance with game score, as described by Baseball-Reference.

Game score is a metric created by Bill James to judge a starting pitcher’s effectiveness in a single game. It uses a system of pluses and minuses to create a score. A score of 50 is considered an average outing. Scores of 0 or below, or 100 or greater are extremely rare.

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The formula for Game Score from the baseball-reference main site is:

Start with 50 points. Add 1 point for each out recorded, (or 3 points per inning). Add 2 points for each inning completed after the 4th. Add 1 point for each strikeout. Subtract 2 points for each hit allowed. Subtract 4 points for each earned run allowed. Subtract 2 points for each unearned run allowed. Subtract 1 point for each walk.

I also separated data points between starters with three or more 120+ pitch games and those with two or fewer to see if the “established workhorses” handled deep outings any more favorably. All starts that were either the last of the season or preceded a relief appearance were discarded.

We’ll kick things off by comparing pitchers’ game scores in a 120+ pitch start and the very next start.

Nothing in this table comes as much of a surprise. The pitchers with more 120+ pitch games tend to be more talented, hence the superior game scores in both the high pitch count outings and their respective following starts. Generally speaking, managers only stick with their starter for 120 pitches if they are mowing down the opposing lineup–in fact, 19.1% of the 204 starts tabulated were complete games–so the game score the next time out will naturally dip regardless of pitch count’s effect.

Needing a better baseline to compare the start after a 120+ pitch game to, I calculated the average game score for the season in which the high pitch count start occurred in. For example, Jake Westbrook averaged a game score of 48 in 2013, 20 points higher than his game score of 28 the start after he logged 124 pitches.

The pitchers with less experience amassing 120 pitches observed virtually no change from their typical season stats. As for those who threw 120+ pitches a minimum of three times, they slightly improved upon their season game score after racking up a high pitch count in their previous start. Is this because taxing one’s arm with more pitches makes you inherently more effective going forward? The answer is almost certainly no. Perhaps these hurlers are simply throwing the ball well and riding a “hot streak” on the heels of their deep–and presumably successful–performance, or perhaps the numbers in the “Difference” column are so slim as to be chalked up to the good ole statistical variance that is so prevalent in this activity we call baseball.

Maybe pitchers are more prone to sudden swings in production their next time out after throwing so many pitches. I revisited the changes in game score from 120+ pitch starts to the game score in following starts, finding the standard deviation to be 21.9. For context, the start-to-start standard deviation in game score for all pitchers, regardless of pitch count, in 2018 is 22.2. Long story short: pitchers don’t appear to be any more or less consistent in the game after running a high pitch count. One interesting nugget was that the standard deviation for the pitchers with three or more 120+ pitch games (16.3) was seven points lower than for those with only one or two (23.3). This group, comprising primarily of aces with All-Star appearances and/or Cy Young votes to their names, could be more consistent across all starts, so additional, more rigorous testing would likely be required to make much of this tidbit.

Please don’t consider this research my endorsement of starts that eclipse the 120 pitch mark. From a pure tactical standpoint, I would be inclined to advocate for the exact opposite. This study does not account for any potential long-term ramifications of repeated high pitch counts, but they evidently do not impact the immediate future as much as we may have initially thought.