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Zach Plesac is getting better by getting down

Using the fastball less has helped Plesac force more groundballs and confound more hitters

Cincinnati Reds v Cleveland Indians Photo by: 2021 George Kubas/Diamond Images via Getty Images

In the last decade, Cleveland has featured some spectacular pitching. In particular, some spectacular ground-ball pitching.

All the way back in 2011, Justin Masterson and the artist formerly known as Fausto Carmona (Roberto Hernandez) were seventh and eighth in MLB in ground-ball percentage (55.1% and 54.8%, respectively). Almost every year since (except for 2014 and 2019), Cleveland’s pitching staff has had a qualified pitcher among the top 25 in ground-ball percentage, including Shane Bieber, Carlos Carrasco, and Aaron Civale all placing in the top 20 last season.

None of those individuals is leading the team in ground-ball rate this year, however. This year’s worm-burner extraordinaire is Zach Plesac, who is running 55.4% ground-ball rate through 40 innings, placing him sixth among all qualified MLB pitchers. This, however, is not the Plesac we’ve grown accustomed to since his debut in 2019.

Though his 2020 season was obviously much shorter than 2019, it had some consistency. For instance, his HR/9 were 1.48 and 1.3 for 2019 and 2020, respectively; HR/FB were 14.5% and 14.0%; fly ball percentages were 38.5 and 40.7%; and ground-ball percentages were 39.1% and 39.3%.

The big change for Plesac in 2020 came in the form of fewer walks. In that shortened season, Plesac lowered his BB/9 to 0.98, down from 3.11 in 2019. The dramatic change came from an increased reliance on his secondary offerings and decreased reliance on the fastball. In 2019 Plesac threw his four-seam fastball 50.6% of the time but lowered that to 37.6% in 2020 and increased use of his slider from 18.8% to 27.8% of his total pitches. The changes didn’t result in Plesac finding the zone more often, as his zone percentage went from 44.3% to 44.1%, but it did result in players swinging much more often — from 47.3% to 52.8%.

With Plesac’s arm angle, using the elbow spiral to keep things tight to the body and provide some extra deception, he is able to tunnel his pitches well and get hitters to commit on them before they leave the strike zone. This is clearly something Cleveland has worked on with the young right-hander, and the results are especially obvious when overlaid.

But making hitters look foolish doesn’t necessarily translate to the remarkable jump in groundballs we’ve seen so far this year. Though only time will tell if Plesac can maintain the 16-percentage point leap, there are signs that he might be a long-term ground-ball pitcher.

First and still most significant, Plesac is limiting the deployment of his fastball. With an average velocity of 93.2 and just 0.1 inches of vertical movement versus league average, the fastball is truly just an average pitch. Opponents do not treat the fastball like average, instead teeing off on it like it’s a batting practice special to the tune of a 212 wRC+ this year.

Baseball Savant

Second, Plesac has continued to use his breaking pitches to great effect. Whereas his fastball lives higher in the zone, his slider and curve hit lower in the zone where they’re more likely to be hit as a groundball and do less damage. To wit, the slider has been a groundball 62.5% of the time, and hitters have a wRC+ of just 13 against it this year. Likewise, the curve is a grounder 43.8% of the time and hitters have a wRC+ of -28 against it in 2021.

Finally, the pairing of the changeup with the slider has paid dividends. Plesac’s slider is harder than league average, at 87.4 mph, but at that velocity, it almost perfectly matches his changeup, at 85.7 mph. Likewise, the slider (yellow in the image below) and changeup (green) follow nearly the same path, with their vertical break measuring -26.1 inches on the slider and -25.7 inches on the change, which is about as perfect a tunnel as any pitching coach could devise.

Plesac’s average pitches from 5/7/21 vs. Cincinnati
Baseball Savant

The two pitches differ in spin rate by 440 rpm (2059 vs. 1619) and have horizontal breaks that are 11 inches apart, with the slider breaking just an average of 0.6 inches and the changeup breaking 11.6 inches. Pairing them the way Plesac has, throwing the slider 25.5% and changeup 22.8% of the time, makes it harder for hitters to prepare or sit on the pitch they want. Even if they do sit on either pitch, good luck guessing which way the ball will break as it exits the tunnel.

Things haven’t gone perfectly for Plesac in 2021, with two bad outings marring his early-season record. But it’s early yet and he could still be working through the changes he implemented last year. If he can continue to baffle batters with his secondary offerings and get them to beat the ball into the ground, though, those changes might just make him one of the most effective out-getters in all of baseball.