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By The Numbers

Weapon Of Choice: New Pitches To Watch

by Matt Williams
Updated On: April 13, 2021, 11:00 am ET

There are many starting pitchers that have altered their pitch mix, or the percentage that they throw each pitch in their arsenal, to begin the 2021 season. Many have increased the usage of their four-seam fastball in order to counteract the cold or lack of “feel” for their secondary pitches. However, many have made a long-term intentional alteration to their attack plan. This is what we want to focus on.

It is important to note that it is very early, and starting pitchers sometimes craft a game plan for a certain team. This cannot be overstated for player evaluation over a small sample size. It does not mean we cannot look to analyze the changes and predict a possible outcome. Another important note is how and when a pitch is being thrown. Every pitch is not being thrown down the middle of the plate so a flat percentage of each pitch thrown does not tell the entire story. Where in the zone is a pitch being thrown? In what count is the pitch being thrown? Is it being thrown to right-handed batters or lefties? These are all important questions when evaluating a pitcher’s arsenal.

As we go By The Numbers today, I am going to narrow down our early season search to a couple of players throwing entirely new pitches: Nathan Eovaldi and Tyler Glasnow. This is to say that there was not a cognitive plan to throw a pitch more or less but to add a new weapon entirely. We will look into how effective new additions to a pitcher's arsenal are individually, as well as how they impact and integrate with the arsenal as a whole. The goal is to give you a head start into searching your own players and learning how to investigate pitch mix changes. We will start with a slightly deep dive into Nathan Eovaldi’s new slider as an example of how you can evaluate a new pitch early in the season.


Nathan Eovaldi, Red Sox


New Pitch: Slider (16.7 percent usage)


Nathan Eovaldi is off to a fantastic start this season with two outings in the books against the Orioles and Rays. The key for the 31-year-old has been health, not talent, so when the right-hander added a revamped slider to his arsenal this season it was noteworthy to investigate.

Eovaldi has thrown a slider in the past, and only recently stopped using it last season, opting instead for an increase in cutter usage. It is important to note that a slider and cut fastball are sometimes interchangeable on research websites, such as FanGraphs and Baseball Savant, depending on the movement and velocity. This sometimes depends on the pitcher themselves and how they decide to classify it. Unfortunately, this may always be a minor issue and simply requires a bit of research if you really want to see it for yourself.

Getting back to Eovaldi, you will notice that the cutter he threw last season, and this season, had a velocity of 91-93 miles per hour while the new slider comes in closer to 85-86 miles per hour. That is an obvious difference that makes our job easy. The question is comparing his 2019 slider to his latest offering. As far as spins rate (RPM) there is only a slight difference between 2019 (2237) and 2021 (2169) while the newest version shows little movement deviation versus the league average.


Eovaldi slider to RHH


In fact, Eovaldi’s cutter has superior movement at a higher velocity. However, they are not used in tandem with the right-hander deploying the cut fastball exclusively to left-handed batters, often low and inside. That seems like a bad idea for what it’s worth as that is typically the power wheelhouse for a lefty, but he also works in the curveball against left-handers. 


Eovaldi vs LHH


The new slider, however, is Eovaldi’s new weapon against right-handers. 


Eovaldi vs RHH


Last season Eovaldi had essentially the same plan of attack for both sides on the plate, elevated four-seam and mixing in cutters and curveballs (low and away to right-handers, and low and into lefties). The only difference this season is the way in which the Red Sox ace is going about it.


Eovaldi Zone Chart


The early returns suggest the new slider is a superior pitch to the one thrown in the past (chart below), but there is not much in terms of tangible proof to suggest the new offering is independently different.


Eovaldi 2019vs2020 Slider


It could be that the new plan of attack to use the slider as a primary weapon against right-handed hitters is a successful one. Remember, Eovaldi threw the slider just 3.3 percent of the time in 2019. On the other hand, this could also just be small sample shenanigans. The plan of attack is the same as always, just with slightly different moving parts.


Whether it was last season or this season, Eovaldi likes to pound the zone with fastballs when he is behind in the count. This is not a revelation and many pitchers do this, but it does make him slightly predictable. 


Eovaldi Count Chart


In 2020 if Eovaldi was ahead of you in the count you were likely to see curveballs low or below the zone, split fingers, or elevated fastballs. This season a batter is still likely to see a diet of four-seam fastballs if Eovaldi falls behind, but once ahead he has been aggressive on the corners while throwing quality offspeed pitches to stay ahead. 


Eovaldi Detailed Zone


Eovaldi has shown in the past how effective his slider can be. In fact, back in 2018, it was his best pitch. It was strange that in 2019 he cut back the usage from 11.1 percent to 3.3 percent only to completely abandon the pitch last season. It’s great to see it back as a major part of Eovaldi’s arsenal, but predictability may hold the right-hander back.

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Tyler Glasnow, Rays


New Pitch: Slider (35.1 percent usage)


The knock on Tyler Glasnow was that he had a limited arsenal, despite success at the major league level. Could he make it long-term multiple times through a lineup throwing just a four-seam fastball and nasty curve?

Luckily we no longer have to wonder.

The 27-year-old unveiled a brand-new, never-before-thrown slider this season. The early results have been encouraging to say the least. Glasnow has now tossed 19 2/3 innings this season with 29 strikeouts to just three walks. Glasnow generated 27 swings and misses during his last outing on Monday night with a 50 percent whiff rate on his new slider.

Last season Glasnow featured a very basic and predictable game plan. Mid to high zone fastballs and mid to low zone curveballs. Right-handed, left-handed, it did not matter (chart below). 


Glasnow 2020


That made the 52.5 percent whiff rate on the curveball all the more impressive. Even when you know it’s coming it was difficult to hit in tandem with Glasnow’s 97 mph fastball. This season hitters do not have that luxury. Glasnow may not have pristine command of his new pitch, as seen in the chart below, but it certainly mixes up the expectations of opposing batters.


Glasnow 2021


Let’s take a quick look at what opposing hitters were used to seeing from Tyler Glasnow. First the curveball, the hook that the right-hander is known for:


Glasnow curve


The bottom drops out and there nothing you can do but lay off of it or swing and miss. The other predictable option from pre-2021 Glasnow was the four-seam fastball:


Glasnow Fastball


It’s tough to catch up to high heat, but with a lack of command and predictable two-pitch arsenal analysts and opposing, hitters could find a way to defeat this plan of attack. Here is a breakdown of Glasnow’s arsenal from the 2020 season:


Glasnow 2020 arsenal


Imagine going to the plate thinking about getting either a 97 mph fastball or an 84 mph curveball with a wicked vertical drop thrown to you. Instead, this is what is thrown your way:


Glasnow Slider


Unfair is a word that comes to mind. Having a legitimate third pitch opens up so many doorways and a brand new ceiling to Tyler Glasnow. A third pitch not only unlocks more strikeout potential but paves the way to go deeper into games. It’s also important not to think of this n a one-dimensional point of view. Just like we did with Eovaldi, you have to think about how this pitch impacts Glasnow’s other pitches. 


Glasnow 2021 arsenal


The new slider is a fantastic weapon, but the most beneficial perk may be how dangerous it makes the rest of Glasnow’s arsenal. The Rays ace has one of the longest extensions in baseball due to his 6-foot-8 frame, meaning he releases the ball closer to home plate than most pitchers. Not only does that make a four-seam fastball that touches 100 mph seem faster, but takes away precious milliseconds from the opposing hitter to make a decision as to what is coming.

This is made more difficult by many major league pitchers through the use of tunneling. Imagine a pitch is released from the pitchers and either fires straight ahead like a fastball or breaks early like a 12-6 curveball. You can pick up the break early and prepare for what is coming. Now imagine a pitch that releases but follows a similar path to the fastball only to break during the last third of the trip to home plate. 


Glasnow Tunnel


Glasnow still has an issue of command that should give him issues at times. Once the 27-year-old is behind in the count, a four-seam fastball is an overwhelming favorite to be thrown. However, if you allow Glasnow to get out in front it could be lights out in 2021.


Glasnow Count


Other Notable New Pitches To Follow


If you want to take the opportunity to take what you have learned and research how new pitches impacted other pitchers' arsenals, here is a list of notable pitches who have added a new weapon in 2021:


New Pitches 2021


Matt Williams

Matt Williams is a baseball writer/analyst for NBC Sports Edge, RotoFanatic and is the author of #2021PlayerBreakdowns on Twitter. He is the host of the Turn Two Podcast & you can follow him on Twitter @MattWi77iams.