Almost two years ago, I wrote about Zach Eflin for the first time. The article focused upon his status as an extreme strike-thrower – a roster spot-saver type starter that was a threat to complete a game despite a relative lack of bat-missing ability.

The game has changed – or more accurately has been changed – since then. We now have a three-batter minimum for relievers, free runners on second base in extra innings, and seven-inning doubleheader games, all designed to shorten games and minimize the stress on bullpens.

Something else has changed since then. Eflin has developed more bat-missing ability while retaining his contact management expertise, and is threatening to become a third ace atop the Phils’ rotation that is led by Aaron Nola and Zack Wheeler.

Late this winter into early spring, I unveiled my annual series on the best individual pitches in baseball. To qualify for letter grades during this exercise, individual pitchers had to qualify for the ERA title (i.e., pitch the equivalent of an inning per game).

The number of ERA qualifiers decreases each season, even in last year’s 60-game Covid-shortened campaign. Only 40 hurlers made the cut. During the 2021 season’s early stages, I figured I’d go back and grade out the repertoires of the 31 starting pitchers who hurled between 54 and 59 2/3 innings in 2020. We’ll go through each pitch and identify the additional “A”/”A+” grade recipients. Earlier this week, we took a look at their changeups, led by the Rays’ Ryan Yarbrough.


First, a little refresher on the methodology. Pitchers are graded on their ability to miss bats and manage contact with their individual offerings. An average pitch gets a “B” grade, and grades diverge up or down from that average based on pitch-specific performance relative to league norms in those two areas. In the pandemic-shortened 2020 season, any pitch thrown at least 100 times, with at least 15 balls put into play qualified for a letter grade.

The two pitchers we’ll cover today, Eflin and the Athletics’ Jesus Luzardo, didn’t clear that batted ball threshold by much, but their results earned them “A+” and “A” grades, respectively.

The curve/knuckle-curve consistently ranks as the game’s third-best offering behind the changeup and slider. In 2020, its swing-and-miss rate of 15.1% and pitch-specific Adjusted Contact Score of 90.2 both ranked third. (Adjusted Contact Score measures, on a scale where 100 equals league average and the lower the number the better, the level of production that should have been allowed based on actual exit speed/launch angle of all balls in play.) The curve’s average ball-in-play distribution of 8% pop-ups, 29% fly balls, 23% liners and 40% grounders closely mirrors that of the slider.

Eflin only threw his curve 13.1% of the time in 2020, and only induced 20 balls in play. His pitch-specific Adjusted Contact Score of 50 ranked behind only one ERA qualifier, Kyle Hendricks, and his 20.8% whiff rate ranked 4th behind only Shane Bieber, Aaron Nola and German Marquez, who all throw knuckle-curves. Bieber and Marquez received “A+” and ‘A” grades. The only other “A” grade recipient among ERA qualifiers was Zac Gallen, yet another knuckle-curve thrower.

Stylistically, Eflin’s curve was much different than those thrown by the other “A” grade recipients. He didn’t throw it as hard (79.2 mph) or with as much spin (2369 rpm). Its average horizontal movement (6.6 in.) was higher than all three, while its average vertical movement (5.4 in.) was far less than Bieber’s and just below Gallen’s.

Eflin posted an impressive 50% grounder rate with the pitch, and also suffocated fly ball authority (28 Adjusted Fly Ball Contact Score). Only Bieber’s (knuckle-)curve was more dominant among regular starters in 2020. Oh, and spoiler alert – another one of Eflin’s offerings received an “A” grade and will be covered here within the next couple of weeks.

Luzardo also featured a dominant curve ball in 2020. Both his pitch-specific Adjusted Contact Score (59) and whiff rate (19.6%) would have ranked 5th among ERA qualifiers.

There’s a bit of disagreement among pitch-identification algorithms on Luzardo’s curve. Fangraphs calls it a slider, Statcast calls it a curve. It possesses the velocity (84.2 mph, 2nd behind only Marquez among ERA qualifiers’ curves) and minimal vertical movement (1.5 in.) of a slider, and both its average spin rate (2533 rpm) and horizontal movement (0.6 in.) were low for either type of breaking ball.

Luzardo threw his curve a bit more often than Eflin (22.8% usage rate), but generated only five more balls in play. His batted ball type distribution was unremarkable, but like Eflin, he throttled fly ball authority (36 Adjusted Fly Ball Contact Score).

His changeup narrowly missed an “A” grade (receiving a “B+”), but Luzardo’s upside will largely be defined by the development of his fastballs (his four-seamer got a “B”, his sinker a “C+”) and his eventual pitch mix. He threw his fastballs 53.2% of the time in 2020, which is high for a pitcher lacking a plus heater.

Click here to see the curve ball pitch grades for the 20 qualifying pitchers who hurled between 54 and 59 2/3 innings in 2020.