The Emergence of Carlos Rodon

Coming into the 2021 MLB Season, Carlos Rodon was far from a household name. Throwing just 232.1 combined innings across the past four seasons, few associated Rodon with anything but the injury bug. Rodon dealt with both wrist and shoulder issues throughout the 2017, 2018, and 2019 seasons, and all of his injury struggles finally culminated in a decision to undergo Tommy John Surgery in May 2019. However, even during periods of health over the past four years, Rodon was far from an elite starter, pitching to a below-average 4.45 ERA, 1.33 WHIP, 4.68 FIP, and 4.68 SIERA in that span. For this reason, few in the baseball world, including his own team, the Chicago White Sox, believed he would ever develop into a great starting pitcher, much less an ace. In fact, the Sox themselves non-tendered him following the 2020 season, ultimately deciding to re-sign him to a much more budget-friendly $3 million contract. However, Rodon has shattered almost every prior perception of himself by emerging as one of the best starting pitchers on the planet in the early part of the 2021 season. As of June 16, he has pitched to a 1.89 ERA, 0.84 WHIP, 2.51 xERA, 2.41 FIP, 2.81 xFIP, 2.60 SIERA, and 30.7 K-BB%, numbers that all rank within the top 10 amongst starting pitchers who have thrown at least 60 innings this season. Not to mention, he even accomplished the historic feat of throwing a no-hitter, holding the Cleveland Indians to zero hits and just one baserunner on April 14. This begs the question: How exactly has Rodon elevated his game to this extent? What specifically about his 2021 repertoire has made him so dominant? The answer lies below.

Any analysis of Rodon’s pitching performance in the 2021 season starts and ends with his 4-seam fastball. Rodon’s 4-seamer is averaging a velocity of 95.7 mph, a career-high mark, and one that places him 21st amongst all qualified 4-seam pitchers. It is also a massive increase from the 91.4 mph he averaged in 2019 and the 92.8 he averaged in 2020. Rodon’s 4-seamer is also getting way less drop, as it is only averaging 12.1 inches of vertical movement, a significant decrease from the 15–17 inches of vertical movement the pitch used to get before this season. This increase in velocity and decrease in vertical movement has resulted in a dramatic increase in the effectiveness of the pitch, as batters are whiffing at his 4-seamer an unreal 31.1% of the time, a mark that ranks 5th amongst pitchers that have thrown the pitch at least 450 times. The effectiveness of Rodon’s 4-seamer is also not bound to a specific region, as he is not only blowing the pitch by batters in the strike zone (28.1 Zone-Whiff%) but also getting batters to swing outside the zone (29.5 Chase %, 42.1 Out of Zone-Whiff%). These three figures are increases over his previous career-high 20.5 Zone-Whiff%, 23.4 Chase%, and 28.6 Out of Zone-Whiff%, achieved in 2017, 2017, and 2020 respectively.

These underlying numbers have yielded a great deal of concrete success for Rodon, as hitters are hitting .175, slugging .294, and have a wOBA of .251 on plate appearances ending in his 4-seamer, marks that rank 6th, 5th, and 6th respectively amongst pitchers who have ended at least 100 PA’s with the pitch this season. Statcast shows that these numbers are no fluke, as PA’s ending in the pitch have an xBA/xSLG/xWOBA of .208/.370/.279, marks that rank 12th, 10th, and 7th amongst pitchers in the same qualification as before. “Run-Value” is a statistic that aims to quantify the exact value of each pitch in a pitcher’s arsenal on a per-pitch basis. So far, Rodon’s 4-seamer has an RV of -15 which is tied with LAD’s Trevor Bauer’s 4-seamer for the highest RV for any pitch in all of Major League Baseball.

However, no great pitcher is limited to one elite pitch, and luckily for Rodon, he has also refined an excellent slider to complement his dominant 4-seamer. In fact, before this year, although Rodon struggled to put together consistent outings, the one thing he was lauded for was a very reliable slider. The pitch registered a negative RV every year between 2015 and 2019 but did take a drop-off in last year’s shortened season. However, this year, Rodon seems to have combined all the elements of the pitch that worked in years past, turning it into a side-dish to his 4-seam main course. The pitch averages a velocity of 85.9 mph, much higher than the 83.4 mph it averaged last year, a figure that places him in the 73rd percentile of Slider Velocity amongst all qualified pitchers. In addition, the pitch is spinning about 2475 RPM(revolutions per minute), very close to the career-high 2495 RPM he threw the slider at in 2018, and in the 71st percentile of Slider Spin Rate this year, amongst all qualified pitchers. By definition, a good slider must register significant horizontal movement, and that is exactly what Rodon’s has been doing this year, as his slider is breaking 8.6 inches on average, a figure that is a whopping 100% better than the league average slider. These metrics have yielded a lot of success for Rodon, as he’s getting whiffs on the slider a remarkable 45.6% of the time, a number that ranks 7th amongst all pitchers who have thrown the pitch at least 250 times. The pitch is also getting hitters to lose discipline at the plate, as he’s generating a Chase rate of 36.8% on the slider, a drastic increase from the 22.2% he got in 2020, and very close to a restoration of the ~38% he used to get in 2015 and 2016 when the slider was his go-to pitch.

Rodon’s slider has also yielded concrete, outcome-based success for him and the White Sox. Out of all pitchers who have ended at least 50 PA’s with the slider, Rodon’s is generating a BA of .051, the lowest mark out of all pitchers in this category. In addition, the pitch also has hitters slugging .063 and hitting to a wOBA of .109, both numbers that rank atop all slider leaderboards. Statcast shows that these numbers are once again not a fluke as hitters are hitting to an xBA/xSLG/xwOBA of .070/.097/.139 on PA’s ending in the slider, numbers that rank 1st, 1st, and 2nd respectively in all of Major League Baseball amongst qualifying slider pitchers. Furthermore, Rodon’s 60.2 K% on PA’s ending in the slider ranks 2nd amongst qualified Slider pitchers, only ranking behind the otherworldly Jacob deGrom. Given these statistics, and the fact that Rodon’s slider has registered a -3.1 RV per 100 pitches, a mark that puts him in the top 5 in the entire MLB, it would be very reasonable to consider Rodon’s slider the most dominant slider in the entire league.

Rodon throws the 4-seamer and the slider a combined 82.5% of the time, as his other pitches, the Changeup and Curveball are not particularly effective. Rodon has found a new formula to wipe out hitters in 2021, combining a high-velocity fastball with a high-movement slider, making him one of the most dominant pitchers in baseball, and one of the best breakthrough storylines in the league. Overall, the Chicago White Sox have high aspirations for this October, and it would not be an overstatement to say they will only go as far as Rodon will take them.