From the Bleachers pt1: Tyler Glasnow
- Chris Atkins
- May 4, 2020
- 4 min read
Most people are not aware of the fact that baseball is a fundamentally mathematical sport, but it makes a lot of sense if you think about it.
If you repeat the same movements over and over again, you are bound to have people start running stats on you. There is a whole field of maths, call sabermetrics, dedicated to the empirical analysis of baseball. It is a very young field, but it is a rabbit hole of knowledge. Companies such as Driveline use highly advanced technologies (Motus, rapsodo, edgetronic, k-vest etc..) to measure athletes' capabilities and find how to improve on their pitfalls.
This is a series of blog post intended to show people that baseball players are creatures of habits and that their performance can be evaluated with statistics. In this instance, we'll take a look at Tampa Bay Rays pitcher Tyler Glasnow.
Tyler Glasnow is one of the most interesting pitcher currently playing in the Majors. European audiences will probably not know this, but it is very, and I can not stress this enough, very hard to make it to the Major Leagues.
Most players who get drafted never even make it. Pitchers, in particular, need to develop an arsenal of different pitches to fool batters. This is even more important for starting pitchers, who have to go several innings, and in so doing need to rely on breaking pitches more heavily than relieve pitchers, who can afford to mostly throw heat (Ken Giles, is good example of this).
This means that most successful pitchers will have 4-5 different pitches when arriving in the Major Leagues, except when your name is Yu Darvish, and you’re badass, and you have an 8 pitches arsenal. But Glasnow is weird. Glasnow basically just has 2 pitches: a fastball, and a curve ball (3 if you count his seldom used changeup).
Now, these pitches are both quite extreme. His fastball speed is within the 95th percentile, and his curveball spin is also in the 95th percentile. This means that his fastball will just whiff past you, and that the curveball will move a lot. Below is a video (courtesy of Michael Augustine) that shows how efficient his pitches are, in part due to spin mirroring.
Also visible are heatmaps of how Glasnow is able paint the strike-zone with his pitches. The curveball is interesting in that it is mostly used under the strike zone. But this is easily explainable as this will be his strike out pitch, and he will try to use its movement to try and get you to strike-out swinging. The fastball is much more precise. He uses it to mostly get some strikes in early in the at-bat, or get back in the count.
Furthermore, as you can see on figure 4, if he falls behind on in the count he is less and less likely to use his curve, but the opposite is also true. If you fall behind, you should expect a CU.
These graphs are particularly telling, but they are not unexpected. Baseball pitchers use sliders, curveballs and mostly breaking balls to strike you out. On the other hand if they fall behind, they will not want to issue a walk and are more likely to go for a less breaking pitch.
Glasnow’s fastball ranked 6 among starting pitchers in major league during the 2019 season. His average fastball velocity lies at 97.6 mph. We can see that, through figure 5, his fastball is usually slower at the start of the season, which is a normal observation for nearly every pitcher. After spending the off-season away from the fields, arms need to get back to their highest form.
From June to July, the average velocity is in constant increase from around 96 to 98 mph. His average speed topped at close to 98.25 mph in August, and then progressively slowed down as the Rays managed to make the post-season in order to preserve his arm for more important October games.
During games, it is interesting to note that he usually throws ever so slightly harder if pitching during the top half-inning rather than the bottom half. In both cases though, we see a gradual decrease in fast ball velocity as innings progress, another expected observations, taking into account pitcher fatigue during a game.
His curveball is more interesting in that the decrease in speed during games is not as perceivable. The curveball is all about the movement, not speed. And if anything, the slower the curveball, the more it can potentially play in your favor.
As to the evolution of the pitch’s speed throughout the year. It is also intriguing to see that there is a local maximum around May, which quickly slows down, to then increase again in August.
The release points of his fast and curveballs are quite similar. For audiences that are not aware of what this means, the solution is in the name.
The release point are the x and y coordinates of the pitcher’s hand at the moment of release the ball during a pitch. Glasnow’s release point lies at about 6 ft of the ground for all his pitches.
As to the horizontal release, if 0 is where the pitcher is standing, Glasnow releases both his FF and CU around 1.5 ft to his right. His changeup is released in a slightly different position, but the small sample size prevents us from drawing any solid conclusion.
Another observation is that, again, as innings progress, he releases his fastball closer and closer to his body and to the ground. But this is not the case with his curveball.
It seems, then, that his curveball is much less subject to physical attrition than his fastball, which loses in both speed, and release consistency.
Even with his 2-pitch arsenal, Glasnow is an amazing pitcher, and the Rays have made him into one of their top pitcher in the MLB. While the fastball/curveball mix offers great opportunities for sequencing exploration and pitch tunneling, a tertiary pitch, with some lateral break, could be helpful.
Thanks for reading, I hope this was helpful, next up will be Yu Darvish.
- Chris
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