Philadelphia Phillies starter Zach Eflin had one of the best starts of his career on Sunday against the Los Angeles Dodgers. Eflin held the vaunted Dodgers lineup to 2 runs on 4 hits while setting a new career-high in strikeouts with 12. It was the 20th start in Eflin’s career that he has gone at least 7 innings and allowed two earned runs or less. 

So, how did Eflin dominate the Dodgers lineup (outside of two solo home runs) and what has him on pace for his best career season? First, we have to understand the type of pitcher Eflin is. 

Sinker is first

Eflin is primarily a ground ball pitcher that aims to induce soft contact in the zone with his sinker. Last season, Eflin threw his sinker 41% of the time and opposing hitters had an expected batting average of .269 against it. Not much has changed in this department, as Eflin is still throwing roughly 40% sinkers and opponents have a .252 xBA against it. However, the noticeable difference from last year is what pitch he is throwing the second most behind the sinker. 

New second pitch

In 2021, Eflin threw his slider the second most at 24% of the time. This season, that has dropped dramatically through his seven starts to just under 5%. The curveball is now Eflin’s second most used pitch as he’s thrown it 18% of the time, up from 10% last season. In fact, this trend can be traced back to 2019. 

via Baseball Savant

Eflin threw his curveball just 5% in 2019. That number jumped to 13% in the shortened 2020 campaign and registered at 11% in Eflin’s injury-shortened 2021. Conversely, Eflin threw his slider 31% of the time in 2019 and that number fell to 20% in 2020 before finishing at 24% last season. As the curveball usage has gone up, the slider usage has gone down.

Trouble with the curve

The most dramatic display of Eflin’s higher use of the curveball was in his start Sunday against Los Angeles. Of his 106 pitches thrown, 35 of them were curveballs, or 33%. That’s just barely below his sinker which he threw 39 times or 37%. Also, Eflin did not throw a single slider to any of the batters he faced on Sunday He did however generate 24 swings at his curve and 12 of them were whiffs.

This pitch is one of the most impressive curveballs on Sunday. Here, Eflin gets Mookie Betts swinging after Betts homered in the previous at-bat off of a sinker. 

The above overlay shows how Eflin’s curveball compliments his sinker when both are working. Both pitches start up but the curve darts down much harder at a slower velocity and in a different direction than the sinker. The curveball drops away from a righty/into a lefty while the sinker does the opposite. If the hitter sits sinker, there’s a good chance they’ll end up swinging over the top of a curveball or hitting the top of it. On the flip side, if the hitter sits curveball, the sinker starts the same but at a higher velocity with less break, most likely leading to a late swing and weak contact. Both of these are ways to generate groundballs, a.k.a. Eflin’s bread and butter. 

Will the trend continue?

That drastic jump in usage against the Dodgers could have been tied into just the feel Eflin had for the pitch on the day and the early success he was having with it. It doesn’t necessarily mean that he will continue to throw the pitch that much. He certainly will not magically become a strikeout pitcher. However, it does illustrate that Eflin has gained a new confidence with the pitch and it’s keeping hitters off balance. If Eflin felt comfortable to use it that much against the best lineup in baseball, look for him to continue using his curveball more in future starts. 


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