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Tyler Glasnow is throwing the ball harder since returning from injury

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Glasnow has been terrific since returning from injury

Boston Red Sox v Tampa Bay Rays Photo by Julio Aguilar/Getty Images

Tyler Glasnow has pitched some of his best baseball since returning from the Injured List with forearm tightness. Before the injury, Glasnow was pitching great (with a 1.27 ERA), but since coming back from injury, he has thrown the ball even better, with his already filthy pitches showing an even higher quality. Let’s take a look at what’s improved.

Before continuing, one thing needs to be made clear: Glasnow has thrown only 8 innings since returning from injury, for a total of 144 pitches in those innings. The sample size we’re working with is incredibly small, so any conclusions made should be done so with multiple grains of salt.

Glasnow has struck out 17 of the 32 batters (53%) he has faced this month, allowing only two runs, which came in his first outing back from injury (on a home run). Glasnow has allowed five hits in total, good for an average against of .172.

Most importantly, he’s building his innings back up and letting everything fly in each of his innings-limited appearances. Additionally, both of his plus-pitches have benefited from this workload, which will now be broken down further.

Four-Seam Fastball

Glasnow’s four-seamer was already a menacing pitch, having been thrown 13 times at 99 mph or harder before his injury. Since returning from injury, however, he’s thrown 99 mph or harder 16 times! That’s up from 3% of his fastballs pre-injury to 14%.

The average velocity of Glasnow’s fastball before injury was 96.6 mph, and that pitch was thrown 444 times. Since then, Glasnow has thrown 112 fastballs with an average velocity of 97.9 mph. Up 1.3 mph on average, Glasnow is unleashing everything he can into his fastball during his shorter outings while he builds his innings back up, and it’s making a difference.

Prior to his injury, the expected batting average against Glasnow’s fastball was .225, which is already a strong number. Since injury, that number is down to .188, which would be his best in a month in his entire career. He’s recorded 11 strikeouts with the pitch since his injury, catching up to the 18 he got out earlier in the season.


Glasnow’s fastball is only half of the story, as the quality of his curveball has also been elevated during this short stint back with the team. While the velocity of Glasnow’s curveball has increased a little bit, sitting at 83.3 mph before injury and 84.4 since injury, the spin rate on the curveball has improved by quite a bit.

Up 137 rpm since injury, Glasnow’s spin improvement from the second half over the first half ranks 13th among 191 qualified pitchers. Prior to injury, Glasnow’s curveball spin averaged 2882 rpm, with it now past the impressive 3000 barrier at 3019 rpm.

11 pitchers have a second-half curveball spin rate over 3000, and Glasnow ranks ninth. His season-average spin rate of 2950 ranks 12th, just ahead of notable names like Justin Verlander and Charlie Morton, but behind pitchers such as Sonny Gray and... huh, Austin Pruitt!

Charted sorted by spin difference between the first and second half of the season

At the end of the day, it isn’t much of a mystery what Glasnow is doing differently: throwing the ball harder knowing he’s working in shorter-inning outings.

Most importantly, it’s working. Glasnow has had top tier pitches from the beginning, but now he’s throwing those pitches with additional purpose, and they’re even more filthy because of it, adding more velocity to the fastball while increasing the spin on his curveball.