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Nathan Eovaldi’s new five-pitch repertoire could bring him to new heights

He brought back his slider for the first time since 2019!

MLB: Baltimore Orioles at Boston Red Sox Gregory Fisher-USA TODAY Sports

Nathan Eovaldi’s Red Sox career has been a bit of a rollercoaster. He went from a World Series hero in 2018, to an afterthought in 2019, to the Sox’ ace in 2020 (albeit mostly due to lack of options). Here in 2021, he’s again expected to be one of the top pitchers on this year’s Red Sox team, and his first start gave us plenty of reason for optimism. The most intriguing aspect of this start, in my opinion, was the new pitch mix he showed off.

From his rookie year in 2011 all the way until 2018, Eovaldi had featured a slider as his most thrown secondary offering. This slider produced great results in his 2018 season with the Rays and Red Sox, allowing the lowest xBA (expected batting average) and the lowest xSLG (expected slugging percentage) out of all of his pitches. However, in his disastrous 2019 season, Eovaldi started to phase his slider out of his repertoire, instead favoring a curveball which he had rarely thrown before. He threw his slider, his best pitch in 2018, just 3.3% of the time in 2019!

The results of this were... Let’s just say not good. His curveball was pummeled to the tune of a .278 xBA and .569 xSLG, and he finished the year with an inflated 5.99 ERA. Clearly, it was time for Eovaldi to go back to the drawing board. I wrote an article before the 2020 season hoping that he would drop the curveball and revert back to his dominant slider, but instead he did the opposite! In 2020, Eovaldi threw his curveball 17.1% of the time, and did not throw a single slider.

As it turned out, this change was incredibly effective, and he finished 2020 with a solid 3.72 ERA. His curveball became his go-to secondary offering, and opponents’ xBA and xSLG numbers against it were on par with curveballs from studs like Shane Bieber and James Karinchak. With how dominant this new pitch mix was for Eovaldi last year, I was shocked to see him throwing his slider again this past Friday. Eovaldi’s most thrown secondary was still his curveball, but he mixed in 11 sliders over 89 pitches.

At first glance, I was a little skeptical of Eovaldi bringing back his slider, partly because of how productive he was without the pitch last year and partly because he was ineffective the last time he utilized both a slider and curveball in his repertoire. However, after the game Eovaldi talked about how he originally abandoned his slider because it was blending in too much with his curveball, but that he worked on his slider a lot this offseason and was able to throw it more consistently for strikes.

If that’s the case and Eovaldi is able to successfully use both pitches, we may have yet to see his best form. Eovaldi’s never really had a true five-pitch mix as a member of the Red Sox, and he could reach new heights if he’s able to achieve that this year. I’m excited to see what he has in store for the rest of 2021.