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Tyler Glasnow debuts elite new slider on Opening Day

The new pitch is real, and it’s bizarrely good.

Tampa Bay Rays v Miami Marlins Photo by Mark Brown/Getty Images

Tyler Glasnow’s new third pitch was the biggest story of the Rays’ 2021 Spring Training. It’s the kind of story one hears every year — the pitcher version of the “Best Shape Of His Life” narratives — and often new pitches don’t amount to much. But for a two-pitch pitcher like Glasnow there’s an extra level of interest, and some of the early reports were ear-catching: On Neil Solondz’s This Week in Rays Baseball podcast, pitching coach Kyle Snyder described it as potentially “a 93 mph cutter.”

Glasnow showed the new pitch in Spring Training games, proving that it was real, but the shape and speed wasn’t consistent, and Spring Training camera angles are poor, which made it difficult to tell exactly what the new pitch was. A slider? A cutter? Something in between? Any good?

But in his first game, Glasnow removed all doubt. He threw is slider for 26 of his 87 pitches, and it was a hard (average 88 mph), 12-6 slider, and it was very, very good. Better than anyone had a right to expect. Its quality was obvious to the eyes, and confirmed by the pitch tracking data.

Let’s start with the data.

In Elite Company

Looking back at 2020 pitch shape data, there are five pitchers who stood above the rest as having what could be called the top 12-6 hard sliders, with an elite combination of mid-to-high-80s velocity and downward movement in excess of what a theoretical spinless pitch would have achieved: Shane Bieber, Drew Rasmussen, Julian Merryweather, Luke Jackson, and Pete Fairbanks.

Elite Hard Sliders
Data from Pitch Info

It’s a bad idea to read too much into early season single-game pitch-tracking data, when compared with previous years. What appears like a significant change can turn out to be just a calibration problem. And the graph above uses Pitch Info data, which measures from a slightly different point, and so is not directly comparable to MLB Gameday data cited below.

Luckily for us, one of those five elite comparisons for best sliders of this certain type, Pete Fairbanks, pitched in the same game, in front of the same Hawkeye cameras.

And that comparison is something else.

First, here’s Glasnow on Thursday. His slider averaged 88 mph and dropped 2.8 inches more than a spinless pitch.

Tyler Glasnow
Texas Leaguers

Meanwhile, Fairbanks’s slider, measured on Thursday and Friday, averaged 86 mph and dropped two inches more than a spinless pitch.

Pete Fairbanks
Texas Leaguers

So to review, Glasnow’s brand new slider was two mph faster and dropped on average nearly an inch more than did Fairbanks’s best-in-league version; this is remarkable.

While we’re here, let’s note that Fairbanks’s fastball has averaged true armside cut so far. That’s new, and interesting, and something to keep an eye on.

Why a new slider?

Tyler Glasnow already had two elite pitches, with a rising four-seam fastball that can top 100 mph and a hard curve that paces the league with its combination of low-to-mid 80s velocity and extreme downward movement. He already paired those with an inconsistent, seldom-used changeup. So where does the new, harder breaking ball fit?

During Spring Training, Rays GM Erik Neander came on the podcast. The whole interview is worth a listen, but his discussion of the new pitch begins at the 31:30 mark, and is especially interesting and substantive:

On days where [the curve is] landing for a strike, the fastball plays 105, and [he’s] getting commits on the breaking ball when the ball’s thrown 50 feet. I’ve never seen anything quite like it . . . But on days where he’s struggling to land the breaking ball for a strike, you can really simplify your approach, and I think with someone like him that has a disproportionate benefit to the hitter.

So the primary goal in developing this new pitch was to pick up easier strikes.

Having a wrinkle that can land in the strike zone at a higher frequency than the bigger breaking ball, that just gives him some more margin for error early in the count when it’s all about throwing strikes above all else.

Basically, a big curve like the one Glasnow throws, with such extraordinary downward movement, is difficult to place in the strike zone. The slider helps solve for that difficulty.

Scouting The Usage

Throwing the slider in the strike zone, early in the count, is a modest goal. But in its first competitive appearance, there was nothing modest about the pitch itself. How did Glasnow use the pitch and how did it play?

Let’s walk through every plate appearance in which Glasnow used the new pitch in his Opening Day start. The best of the bunch will be embedded below.

Corey Dickerson grounds out to first baseman Yoshi Tsutsugo.

The first time Glasnow threw his slider was in a 2-1 count to the Marlins leadoff batter, Corey Dickerson, and it was a great one. Behind in the count, he started it in the zone, but its movement buried it beneath Dickerson’s swing.

Glasnow immediately went back to the pitch, and left the second one in the zone. This slider had initial upward trajectory that made it more easily identifiable, and having seen it already Dickerson was able to put bat to ball. But the good downward movement still brought it to the bottom half of the bat for a weak groundout.

Starling Marte strikes out swinging.

Against he next batter, Glasnow showcased exactly what Neander said the pitch was for. With an 0-1 count, Glasow placed a slider up in the zone, and Marte fouled it off, bringing the count to two strikes.

Then, in a 1-2 count, Glasnow placed it perfectly in the classic righty-on-righty slider location, sweeping down and away, and there was nothing Marte could do.

Jesus Aguilar “singles” to third base

The next slider was the most instructive one, not because it was more special than any of the others Glasnow threw, but because of the reaction from former-Ray Jesus Aguilar. Glasnow gave him a first-pitch 88 mph slider, right down the middle of the zone. Aguilar knows Glasnow, and not just from the scouting report. And he knows that this pitch was not in the old scouting report. And he knows elite pitch shape when he sees it.

So he reacts appropriately, and laughs.

Glasnow would throw the same pitch a second time immediately after the first, and Aguilar recognized it, but once more that good downward motion resulted in a topped ball for a strike. This at bat would end with a grounder to third base and a Yandy Diaz cleat stuck in the turf, resulting in the only “hit” of the night for the Rays ace.

Adam Duvall flies out to center field

With a man on, Glasnow tried to keep the ball away from Adam Duvall, who swung at neither of the sliders he saw, wisely so, as both were out of the zone. The first was more competitive than the second, might have been tricky for a lesser defensive catcher.

Brian Anderson grounds out

In an 0-1 count, Glasnow tried to frontdoor the slider, but didn’t quite manage to break it back over the plate. It will be interesting to follow what level of feel he has for how to vary speed and break on his new pitch. This one came in at 89 mph. If it had been slightly slower it’s probably a strike.

Jorge Alfaro strikes out swinging

For the first pitch of the at bat, Glasnow broke off a wicked, diving 89 mph version his slider, just below the zone, but Alfaro didn’t bite.

So he used the pitch again to get back into the count, frontdooring his next one into the heart of the zone.

Glasnow nearly put him away later in the at bat with another slider down and away would get foul tipped off Zunino.

Sandy Alcantara strikes out swinging

This is the example that demonstrates how the slider can open up an area of the zone that Glasnow didn’t really have the tools to work in before. His high fastball and low curve made Glasnow a primarily north-south pitcher, but this slider is thigh high, running off the outer edge of the plate for the strikeout. It’s east-west pitching, and it’s something else batters now must worry about once they get to that two-strike count.

Corey Dickerson grounds out softly to first base

After letting one slider drift up and away, Glasnow dropped another one into the zone that Dickerson could only foul off, again challenging the heart of the plate.

Starling Marte strikes out swinging.

The one slider to Marte this at bat was way up and in, chin music.

Jesus Aguilar grounds out to second base

Glasnow fluttered one slider in middle-high at the top of the zone that didn’t get the call to start off Aguilar, but he was able to move the next one down and to a better spot in on the hands for a frontdoor strike. Then, having shown Aguilar the pitch twice up in the zone, he brought it down lower, which induced a swing. In this location, it’s a whiff pitch.

Adam Duvall pops out to first base

Up and away to a right-handed hitter, this slider wasn’t competitive.

Brian Anderson flies out to right field

But in a 1-1 count, this one was perfect. Anderson took it on the corner for a strike, but wouldn’t have been able to do anything with it if he had swung.

Jorge Alfaro grounds out to second base

Glasnow started Alfaro with another good pitchers’ pitch slider on the outside edge taken for strike one.

Then, with Alfaro now knowing that he needed to protect the outside edge, Glasnow took it a step down and off the plate into an unhittable position for the whiff.

He continued to attack the outer edge, inducing a weak grounder with Alfaro forced to protect with two strikes.

This sequence of three was tremendous pitching; extremely unfair. If he’s able to throw a pitch this good and locate this well consistently, expect the slider to remain a big part of Glasnow’s plan going forward.

Miguel Rojas called out on strikes.

Once more Glasnow landed a perfect pitch on the bottom outside corner, to run the count to 0-2.

Magneuris Sierra called out on strikes.

The final slider of Glasnow’s night was not as good as the previous four, but in its own way demonstrates just how much the quality of stuff gives Glasnow that additional margin for error Neander said he was seeking.

Facing a lefty, Glasnow employed it more as a cutter, up in the zone coming in on the hands. He didn’t get it in far enough, and with a good hitter whose seen the pitch enough times, this might qualify as a hanger. But at 89 mph with significant movement, it’s a pitch that can stand on its own feet most anywhere in the zone, and with Sierra also both on the lookout for high-90s and low-80s, he wasn’t able to sit cutter and time it up.


With one major league game in the bag, Tyler Glasnow’s new slider is an amazing success story. It’s fair to be skeptical of new pitches. Simply maintaining oneself as a major league pitcher with the ability to repeat the pitches one already throws is hard enough, so it’s not often that pitchers make significant improvements to their repertoire over the offseason, but Glasnow appears to have done just that.

Eventually this pitch will get hit, but most of the time it won’t.

Not only is his new pitch real, its shape places it squarely among the best hard sliders of the game, and in its debut, Glasnow was able to command it to high quality spots throughout and around the strike zone.

Maybe we should have expected this — Glasnow is already able to get natural cut on his fastball, and his curve demonstrates elite breaking ball arm talent. A hard slider is the logical center point between the two.

The next test for Glasnow, who pitches tonight against the Red Sox, is consistency.