AL EastAnalysis

The Surprising Success of Nestor Cortés in 2021

While the Yankees were having what can only be described as a roller coaster of a season, one of their players who didn’t was Nestor Cortés. Cortés was called up following the injury to Corey Kluber and he never looked back. He wound up with 22 appearances and 14 games started for the Yankees. In those games he allowed a 2.90 ERA, 3.78 FIP with career highs in K/9 (9.97), BB/9 (2.42) and HR/9 (1.35). Not bad for a guy who was signed as a minor league free agent back in December of 2020.

While 2021 was a good year, the previous couple of years do not share the same story. In 2020, he had a 15.26 ERA which was in only 7.2 IP with Seattle, in 2019 he pitched for the Yankees where he sported a 5.67 ERA and a 5.57 FIP in 66.2 IP. Not ideal at all. Given his lack of success there definitely appears to be some changes to his game and luckily some of the changes he made really payed of.

On the surface it does suggest that Cortés made some repertoire changes. If we look at Cortés’ Baseball savant profile it shows that he added a Cutter this season. Prior to 2021 he was mostly a Four-Seam (FF)/Slider (SL) type which engulfed about 80% of his pitches in 2019/2020. In 2021 he threw 42.8% FF (ranged from 40% to 45% in his previous years) but he threw his SL 20.1% in 2021 (down from 50% in 2020 and 34.1% in 2019) and his Cutter (FC) 23.6% while also sprinkling in a Changeup and Sinker. Cortés kept his FF usage unchanged while introducing his FC and reducing his SL usage simultaneously. However if you were to download the play-by-play data yourself you will find that he throws a Curveball as well, in a addition to his FC and SL. The color-coded points in the graph below below illustrates this:

Now these are where the questions will begin to rise. I have the horizontal and vertical movements of each pitch Cortés has thrown this year plotted here. I have ellipses indicating where the Curveballs and Cutters should be in relation to each other with one slight problem, we have sliders sprinkled throughout both groups. Is the second year old system – Hawkeye – having trouble determining whether Cortés’ SL should be a CU or a CT? Or should those CU’s be classified as SL’s given his Baseball Savant profile does not include CU as a pitch that he throws? Or is it just a whole different pitch?

Is it a Slurve?

My initial conclusion lead me to believe it was possible that he morphed his Slider/Curveball into a Slurve. It was easy to conclude this given that my intial evidence came from the graph above which showed how the Sliders were not that distinguishable from Curveballs. Why else would there be arguably a pitch thrown with the same horizontal/vertical movement yet have a different classification by Hawkeye? Another reason was the fact that there have been quite a few Yankees pitchers who have thrown Slurves. Dellin Betances, Michael Pineda and… one of the most recent guys… Corey Kluber. I was not thrilled with this conclusion so I decided to look at plots of pitchers who also throw Slurves:

Doesn’t exactly drive the idea home. A simple analysis on both Yu Darvish and Corey Kluber’s pitch movements indicate various differences between most of their breaking pitches. Both pitchers have clear differences between their Cutter and Slider/Curveball. This is completely different from Cortés’ plot which shows overlap between similar breaking pitches. This is obviously not a Hawkeye issue and whether Cortés has added or tweaked one of his pitches to be a Slurve or not, it is not the reason for why those pitchers have similar movements to one another. Also, in regards to the Baseball Savant profile only including a Slider and not a Curveball, I believe it was tweaked to where the Curveballs were classified as Sliders, based on my judgment.

Arm Slot(s)

In terms of explaining the distribution of Cortés’ SL movement, it seems to have stemmed from throwing his breaking pitches from various release points. When we look at the pitchers with the highest standard deviation of Sliders thrown from the vertical release point (release_pos_z in Baseball Savant) we get the list below:

Nestor Cortés has the third highest standard deviation. Meaning he has one of the highest distributions in which he throws his slider. Rich Hill and Wade Miley are among the other pitchers included within this group who throw their sliders from various release points as well. How does this distribution look visually?

Cortés has a few outliers that are making his distribution much bigger than it is, but there is still a stark range from which he has released his Slider from. Hill has the most unique range out of all the pitchers included, he has thrown Sliders from what could appear as a sidearm delivery to a high 3/4 arm slot. Iglesias and Miley both have two different groups in which they threw their Sliders.

It is important to note that for most of these pitchers, depending on the month, they did not necissarily release the ball at a specific arm slot. The lower vertical release point Sliders that Miley has thrown, were mostly thrown in August and September however, these months also had his biggest distribution of Sliders release points on the year. This is different from the beginning of the year where he had a much higher vertical release point on his Slider. It appears that Miley tried to vary his arm slot later into the season.

The same can be said for Cortés slightly. A majority of his lower release point Sliders came in September but the rest of the distribution were not limited to just one month. Hill, Bassitt and Iglesias all had varying release point distributions throughout each month that they have pitched, so it appears a majority of these pitchers sought to vary their arm slot release points by design and it was not just a product of changing their delivery in the middle of the year, except for maybe Miley.

Now that we visualized their release points what does their movement look like?

As the various Horizontal/Vertical movement graphs indicate, depending on different release points, your Slider can look much different than how it should. There are some similarities with Cortés’ SL (didn’t include the graph in this group because it’s already showcased in the beginning of the article) and the others. Cortés’ Slider overlaps multiple pitches and while nobody else on the graph comes close to his, some pitchers do have pitches slightly overlapping others. Rich Hill probably has the most unique release point range out of anybody as seen earlier and depending on the release point, Hill’s SL and CU have similar movement to each other which is exactly what Cortés has been able to emulate. The big difference is that Hill also includes a traditional CU that has vertical movement. Chris Bassitt almost creates two groups within his Slider grouping where one of them is similar to a Cutter while the rest are just within their own Slider group. Miley’s breaking pitches all can be differentiated but there is some slight overlap between the Slider and Cutter.

For guys like Hill, Cortés and Miley this approach makes a lot of sense. These pitchers do not throw the ball hard so they have to rely on pinpoint accuracy around the edges and deception to stay successful in today’s game. The best deception out there is when you can throw similar pitches at different arm angles. This will create different spin (altering arm angles can also alter the spin axis at which the ball is thrown at) and therefore movement which will keep the hitter guessing what pitch was or is being thrown. While these pitchers are able to create different movement on the same pitch, Cortés definitely stands out the most here.

What did it do to his?

To put it into perspective I will first compare him to a pitcher Yankee fans will probably not want to hear again and that is Andrew Heaney. Heaney is a flyball pitcher and Yankee stadium does not exactly bode well for flyball pitchers. Since August 1st Heaney allowed the 4th highest Flyball% in the league ( 53.8%) with a 3.28 HR/9 which is 2nd worst in the league (minimum 30 IP). In the same time frame, Cortés allowed a 55.5% flyball rate (2nd highest) with a 1.94 HR/9. Both LHP’s, Cortés had a much higher flyball rate yet a much lower HR/9. While almost counter-intuitive to hear, it’s very impressive to say the least.

He allowed the lowest Barrel% of his career, and he allowed the highest Under% of his career as well. That is , basically getting under the ball. This lead to a 23.1 degree average launch angle overall and a 29 degree launch angle on his Slider. Despite the high rate of flyballs, they were not barrelled up but merely flyouts. He also induced a higher whiff% on his Slider than his previous couple of years which was helped by adding about 8.6 inches of break to it this year. He had a 27.5% K rate and a 6.7% Walk rate, which is very ideal and indicative of not only his ability to stay within the strike zone but having deceptive stuff.

Throwing the Slider with multiple release points has allowed Cortés to create different types of movement to deceive the hitter, and with the addition of his Cutter it only helped by creating more confusion for the hitter in the box, forcing the batter to guess on the pitch through velo and spin. This successful one year is the outlier year (so far) in his career, so there can be doubt as to whether he can maintain this success in the future. But success like this doesn’t just happen out of nowhere. While many pitchers have benefitted from altering release points. Iglesias had a stand out year this year, Miley threw a no-hitter this year, Hill is still pitching in his 40s, and Bassitt will be a dominant pitcher for years to come. Cortés has a real ability to be very deceiving and if he maintains this edge he can be a very stable option for years to come.

Photo courtesy of the New York Yankees Twitter account: @Yankees

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