Scott’s Miscellany – Matt Harvey and High-Stress Pitches

The title of the article is an allusion to Schott’s Miscellany, which you should definitely check out if you never have and feel compelled to know that a group of larks is called an exaltation or that a member of the 32nd degree of Freemasonry is known as a Sublime Prince of the Royal Secret.

Matt Harvey and High-Stress Pitches–

Like most of the baseball world, I’m fascinated by Matt Harvey and the question of whether it is worth it for him to exceed his surgeon-prescribed innings limit because of the Mets’ place in the standings this year. To start, let me stress that I have absolutely no medical training. As a layman, I find it interesting that we rely on innings pitched as the barometer of stress for a pitcher. I expect the reason we do that is because innings pitched is the most accessible measurement of how much pitching a pitcher did. Innings pitched no doubt correlates well with total pitches thrown, so there is little lost by relying on the easier stat to find. Still, would pitches thrown even be the best way to capture the stress a pitcher faced?

I’m not the first person to ask that question. The reason I’m writing this article is because I’ve seen several quotes about Harvey—also from laypeople—that suggest that it is the stress of the pitches as much as the quantity that could threaten the health of his surgically repaired ligament. If that is the case, we can study it. To my mind, a pitcher would become more stressed when the game situation he faced became more important. Fortunately, FanGraphs already has a statistic for the importance of a game situation. It is called leverage index (LI).

To get at the answer I was looking for, I calculated leverage index independent of what you can find on the site, but the logic I used is much the same. First, I calculated the win expectancy of every state of inning, inning half (top or bottom of the inning), outs, baserunners, and score differentials based on how frequently teams in those states won those games since 2002. To help maintain sample size at the extremes, I replaced every extra inning with the ninth inning and replaced any score differentials over five runs with five runs. Then, I calculated leverage index by finding the standard deviation of the change in win expectancy from the start of at-bats to the end of at-bats and scaling that to the standard deviation of every start of an at-bat to the end of that at-bat.

Once I’d calculated the leverage index of every at-bat, I then assigned that leverage index to each pitch within the at-bat. Finally, I’m relying on the glossary recommendations of leverage indices of 2.0 or more as high-stress pitches and leverage indices below 0.85 as low-stress pitches.

In the end, Harvey was in the middle of the pack. 436 of his 2,528 pitches this year have been high-stress pitches. That is the 48th-most of the 81 qualified starters. That means that 17.2 percent of his pitches have been high-stress pitches, which is tied for the 27th-highest rate of the 81 qualified starters.

Here are the starters with the most high-stress pitches this season:

Most High-Stress Pitches, 2015
Pitcher Pitches High-Stress Pitches High-Stress Rate Low-Stress Pitches Low-Stress Rate
Jordan Zimmermann 2833 574 20.3% 1690 59.7%
Wei-Yin Chen 2692 571 21.2% 1535 57.0%
James Shields 3107 570 18.3% 1786 57.5%
Chris Archer 3170 560 17.7% 1956 61.7%
Tyson Ross 3025 548 18.1% 1883 62.2%
Julio Teheran 2953 547 18.5% 1795 60.8%
Edinson Volquez 2928 535 18.3% 1710 58.4%
Wade Miley 2869 532 18.5% 1642 57.2%
Chris Sale 3000 529 17.6% 1760 58.7%

Here are the starters with the highest rate of high-stress pitches this season:

Highest Rate of High-Stress Pitches, 2015
Pitcher Pitches High-Stress Pitches High-Stress Rate Low-Stress Pitches Low-Stress Rate
Wei-Yin Chen 2692 571 21.2% 1535 57.0%
Jordan Zimmermann 2833 574 20.3% 1690 59.7%
Mike Pelfrey 2439 472 19.4% 1407 57.7%
Matt Garza 2378 442 18.6% 1383 58.2%
Wade Miley 2869 532 18.5% 1642 57.2%
Julio Teheran 2953 547 18.5% 1795 60.8%
John Danks 2599 477 18.4% 1633 62.8%
Edinson Volquez 2928 535 18.3% 1710 58.4%
Jon Lester 2866 525 18.3% 1651 57.6%

And here are the starters with the lowest rate of high-stress pitches this season:

Lowest Rate of High-Stress Pitches, 2015
Pitcher Pitches High-Stress Pitches High-Stress Rate Low-Stress Pitches Low-Stress Rate
Jake Arrieta 3036 377 12.4% 2063 68.0%
Marco Estrada 2510 322 12.8% 1639 65.3%
Anibal Sanchez 2523 337 13.4% 1723 68.3%
Carlos Carrasco 2487 340 13.7% 1568 63.0%
Mike Fiers 2725 379 13.9% 1696 62.2%
Alex Wood 2576 363 14.1% 1516 58.9%
Danny Salazar 2743 388 14.1% 1802 65.7%
Mark Buehrle 2500 365 14.6% 1594 63.8%
Jacob deGrom 2803 418 14.9% 1761 62.8%

We hoped you liked reading Scott’s Miscellany – Matt Harvey and High-Stress Pitches by Scott Spratt!

Please support FanGraphs by becoming a member. We publish thousands of articles a year, host multiple podcasts, and have an ever growing database of baseball stats.

FanGraphs does not have a paywall. With your membership, we can continue to offer the content you've come to rely on and add to our unique baseball coverage.

Support FanGraphs




Scott Spratt is a fantasy sports writer for FanGraphs and Pro Football Focus. He is a Sloan Sports Conference Research Paper Competition and FSWA award winner. Feel free to ask him questions on Twitter – @Scott_Spratt

newest oldest most voted
Luuuc
Guest
Luuuc

Can we see the full list of 81 qualified starters? Also any plans to track this through next year to see if there is anything predictive in this?