Tyler Glasnow, Aflame

When a meteoroid strikes the top of the Earth’s atmosphere, it’s traveling at an unthinkable speed — something like 30 miles per second. Though it’s initially as cold as the void of space, the friction of striking the atmosphere creates intense heat. The thermal energy is sufficient to vaporize it, layer by layer. If the meteoroid survives long enough to strike the Earth’s surface as a meteorite, its outer layer will be blackened beyond recognition. I learned all this on Wikipedia today, because I wanted to understand what it must be like to face Tyler Glasnow.

Tyler Glasnow is a singular pitcher. He stands 6-foot-8, one of only three current major league pitchers that tall. He throws a 97.4 mph fastball. Among starters, only Noah Syndergaard throws harder. It’s not so much that Glasnow releases the ball tremendously high in the air; he’s a long strider, which lowers his release point. It’s more that there’s no one in baseball who throws quite like Glasnow throws — at extreme velocity, with extremely long levers, from a unique release point. Glasnow’s perceived velocity is second only to Jordan Hicks — his fastball explodes towards batters.

As if that weren’t enough, Glasnow’s curve has long been above-average. Want to know how long this has been the scouting report on Glasnow? Take a look at what Eric Longenhagen had to say about him before the 2017 season: “Glasnow’s scouting report has read the same way for the last four years. He throws hard, has touched 100 in the past (I have him maxing out at 97 this year) and spins one hell of a curveball — a potential plus-plus curve, in fact.”

The knock against Glasnow has always been control. In the minor leagues, he often ran double-digit walk rates, and when he got his first extended playing time in the majors in 2017 he walked 14.4% of the batters he faced. Glasnow was a project — and there was hope that his command would come. Here’s Longenhagen again: “That said, there are reasons for patience with the command. Glasnow’s velocity exploded in pro ball, and it’s not easy for someone to quickly learn how how to harness and command that kind of newfound arm speed — and even more difficult when the prospect in question is built like a giant whooping crane.”

Tremendous animal description aside, that was always the book on Glasnow. When he throws strikes, he’s hard to deal with. And in 2018, he started throwing strikes. A mere two starts after he was traded to the Rays last year, Jeff Sullivan noted a change in Glasnow’s strike rate, as well as that old analytical standby, aiming a four-seamer at the top of the strike zone. It might have been hard to tell in the numbers (Glasnow compiled a 4.2 ERA and 4.38 FIP with the Rays last year), but the stage was set for his breakout 2019.

Baseball analysis isn’t supposed to be this straightforward. For the most part, pitchers are good because of interlocking factors that are difficult to separate. For Glasnow, though, locating the ball in the strike zone changed everything. Glasnow has put a higher percentage of his fastballs in the strike zone every year since entering the majors. Despite that, it’s as hard to hit as ever. Take a look at Glasnow’s fastball zone rate and fastball whiff rate over time:

Glasnow’s Fastball Over Time
Year FB Zone Rate FB Whiff Rate
2016 49.1% 24.8%
2017 54.6% 12.5%
2018 56.3% 23.3%
2019 59.6% 19.5%

Even as batters get to swing at fastballs in the strike zone more often, they aren’t really getting better at hitting it. Glasnow can throw in the zone with impunity, and he’s taking advantage of it. He’s getting ahead in the count 0-1 64.2% of the time this year, 6% higher than last year. He’s absolutely living in the strike zone — his 50.3% zone rate on all pitches is fifth among starters. Want to limit walks? Throwing a ton of strikes and getting ahead in counts is the best way to do it.

Despite Glasnow pounding the strike zone, though, batters can’t get the bat off of their shoulders. Among pitchers who have thrown 100 pitches this year, Glasnow is in the 24th percentile in zone swing rate. In other words, batters swing at his strikes less often than 76% of major league pitchers.

Why is that the case? Well, as David Laurila chronicled this week, Glasnow throws his fastball two different ways. This makes it hard to use any average measurements of its movement — Glasnow’s four-seamer with cut moves very differently than his straight four-seamer. No, the best way to understand Glasnow’s fastball is to watch it. Take a look at a called strike that had Christian Vazquez starting and stopping:

You can see why batters have a tough time swinging at that. Next, watch him work the other side of the plate and freeze Vazquez again:

Those two pitches exemplify the conundrum hitters face with Glasnow’s fastball. The movement of the fastball that goes inside to a right-handed batter is befuddling — with Glasnow standing on the first-base side of the rubber and getting arm-side break, it must give the impression of coming right at the batter’s elbow. The outside corner, meanwhile, comes with significant cut. It’s almost like an optical illusion — one minute you think the ball might hit you, the next it’s on the other side of the plate.

It’s no surprise that Glasnow is getting a lot of called strikes with his fastball this year — as I mentioned above, he’s throwing in the zone more and batters are swinging less. His breaking ball command looks vastly improved as well. Take a look at this curve, and you can see the early resemblance to his fastball:

By the time poor Renato Nuñez realizes what’s happening, it’s too late. That pitch, a breaking ball that holds the strike zone, is something Glasnow is increasingly featuring this year. It makes perfect sense — Glasnow’s fastball induces takes and makes batters decide what to do quickly. Pairing that with a secondary pitch that can get called strikes is just sound tactics.

What’s most remarkable to me about Tyler Glasnow’s success this year is how normal it feels. He has a huge fastball, and he pounds the zone with it. His breaking ball works naturally off of his fastball, and he can throw it for a strike. We haven’t talked about his changeup, but it’s a 93 mph changeup with seven inches of horizontal separation from his fastball — sheesh. If you wanted to draw up a three-pitch right-hander in the lab, you’d basically come up with Tyler Glasnow.

What’s amazing about that fact is that Glasnow’s pure stuff doesn’t seem to have changed much. He’s always had the beautiful curveball. He’s added a bit of velocity since his prospect days, but by the end of 2017, his fastball was sitting 96-97 mph. Despite all of that, he only struck out 18.4% of the batters he faced as recently as 2017. All that’s really changed is that Glasnow is locating his two plus-plus pitches in the strike zone more often.

Go looking for evidence of Glasnow’s improved command, however, and you’ll struggle to find it. 3-0 counts seem like a great proxy for command. Batters aren’t going to swing, so as a pitcher all you really need to do is get the ball over the plate. With the caveat that it’s a tremendously small sample size (5 3-0 counts in 2019 so far), Glasnow hasn’t really improved, though:

Glasnow’s 3-0 Zone Rates
Year 3-0 Zone %
2016 37.5%
2017 69.6%
2018 64.0%
2019 60.0%

League average is around 61%, so it’s not even like he struggled overmuch with it in his wilder days.

Okay, fine, so 3-0 counts aren’t telling us anything. What about all counts where the batter is ahead? This is a time when hitting the zone is at a premium:

Down-in-count Zone Rates
Year Zone Rate
2016 53.5%
2017 53.9%
2018 57.3%
2019 58.5%

Well, here you can at least see an improvement. Still, though, it’s hard to look at that and say anything conclusive. Glasnow’s overall zone percentage is up 7.5% from 2017, so his gotta-get-over pitches haven’t improved at the same rate as his overall aggression in the strike zone.

There’s clearly something to Glasnow’s control, as scouts have always mentioned it, but it’s hard to tease out in the numbers. Could it be as simple as a change in approach? Above, I noted that he’s been getting first strikes more often. Take a look at Glasnow’s first-pitch zone rate:

First-Pitch Zone Rates
Year Zone Rate
2016 52.8%
2017 48.5%
2018 56.4%
2019 58.4%

Now we’re talking. Pitchers as a whole venture into the strike zone on around 52% of their first pitches. Early in his career, Glasnow was right there with them. Recently, though, he’s made a switch. With his velocity, you can see why he’d want to do it. It’s just a matter of executing, and for whatever reason Glasnow has that down this year.

The story of a breakout is supposed to be a story of something changing. Maybe it’s a new pitch or a new approach. Maybe it’s newfound velocity. Often it’s multiple things. There’s no arguing that Tyler Glasnow has broken out this year — if the sub-two ERA doesn’t convince you, the phenomenal strikeout and walk rates will do the trick. The truly amazing thing is that he didn’t need to change his stuff to reach this dominant level.

Tyler Glasnow threw a literal-rock-from-outer-space fastball in 2018. He threw a knee-buckling curve. Despite all that, he compiled an ERA and FIP above four. Then he started throwing his fastball in the strike zone more and became one of the best pitchers in baseball. Sometimes it doesn’t need to be more complicated than that.

There are questions left to answer. Glasnow still leans heavily on his top two pitches — he’s thrown his changeup less than 5% of the time this year. He may never consistently go deep into games — he’s facing batters a third time through the order at the highest rate of his career this year and is still in the bottom half of baseball in that metric. Heck, his swinging strike rate has actually gone down year-over-year. The Tyler Glasnow conundrum isn’t yet solved.

Still, though, it’s easy to look at Glasnow right now and nod your head. Why shouldn’t he be great? Why shouldn’t he keep up his current level of performance for the rest of the year? Tyler Glasnow’s real greatest accomplishment this year is that he’s making pitching make sense. In every year before this one, you could look at his stature and pitches and expect him to be dominant, then spend the rest of your time figuring out how he could unlock his potential. This time, though, the results agree with the eye test.

We hoped you liked reading Tyler Glasnow, Aflame by Ben Clemens!

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Ben is a contributor to FanGraphs. A lifelong Cardinals fan, he got his start writing for Viva El Birdos. He can be found on Twitter @_Ben_Clemens.

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Chaise Kahlenbeck
Chaise Kahlenbeck

My thumb hurts watching the catcher get around 98 on the inner half…

Excellent analysis. I think it’s also interesting to note that he’s working with a former pitcher-turned-pitching coach who is also 6′ 8″; coaching can sometimes be overrated but it must be nice to be hearing something from someone who is similar to you in stature.

The Archer trade looks worse every day for the Pirates.


I think you’ve really nailed it with the change in pitching coaches. I recall this exact point being brought up when the trade was announced. I’m glad it has worked out (so far), because it’s fun to watch a potentially dominant pitcher go out there and dominate.