Ed. Note: This was written before Eovaldi’s debut Friday night.
The Red Sox’s acquisition of Nathan Eovaldi in 2018 proved to be instrumental in securing their World Series title. He was solid in 111 innings that year between Tampa Bay and Boston, finishing with a 3.81 ERA for the regular season and dominating throughout the postseason. However, 2019 was a different tale for the righty. He struggled with injuries, was moved to the bullpen, and his ERA ballooned to a career-worst 5.99.
What changed from 2018 to 2019? The big thing that stands out to me was his lack of control. Eovaldi walked just 4.4 percent of batters in 2018, but that number inflated to 11.6% last year. Of his three most-thrown pitches (fastball, cutter, and curveball), he had significant problems throwing two of them. Statcast has a metric called ‘In Zone Rate’, which, as you can probably guess, measures the number of pitches thrown in the strike zone. Eovaldi’s cutter went from an In Zone Rate of 60.1 percent in 2018 all the way down to 49.1 percent in 2019. His curveball’s rate similarly dropped 8 percentage points.
His loss of feel for his cutter appears to be a significant factor in his disappointing year. As mentioned above, he struggled with the cutter’s location, but he also gave up lots of loud contact with it. After allowing a .388 expected slugging percentage and an average exit velocity of 88 mph using his cutter in 2018, those numbers swelled to .528 and 92.3, respectively. Dealing with injuries definitely could have affected this, but regaining a feel for his cutter will be essential for a more productive 2020.
Eovaldi’s pitch mix in 2019 also seemed peculiar to me. His split finger and slider have always been his go-to off-speed pitches, but he seemingly replaced his slider with a curveball. After throwing a curveball just 3.9% of the time in 2018, that number shot up to 17.5% in 2019. This did not reap any benefits, however, with the pitch being crushed to the tune of a .258 expected batting average and a .588 expected slugging.
With his curveball proving to be ineffective, my hope is he turns back to his slider more often in 2020. He threw it just 40 times last year! His slider was great in 2018, providing a minuscule .174 expected batting average and a .268 expected slugging, which makes him abandoning it in 2019 that much more curious.
Despite all of the worry about the pitching staff, I’m excited to see what Eovaldi can bring to the table this year. Hopefully we see some of these adjustments and improvements as the season progresses.
(Ed. Note: In that first game, Eovaldi was more successful with his cutter, and didn’t really throw many breaking balls. When he did, though, it was a curve as he finished the game with four curveballs and no sliders, per Baseball Savant.)