In Tyler Glasnow‘s start against the Atlanta Braves on Monday, he produced around an extra inch and a half of rise on his four-seam fastball compared to his average in 2019. Below is a look at his short-form movement from 2019 and his lone 2020 start:
When a player’s fastball is getting an additional rise, it’s usually due to some combination of adjusted spin direction, altered gryo degree, and/or different arm slots.
An uptick in either velocity and/or spin rate can also help but are more a means to an end. To wit, Glasnow’s Bauer Unit score increased from 23.9 in 2019 (97 MPH, 2279 RPM) to 25.3 (98 MPH, 2476 RPM) during his outing against the Braves.
Glasnow’s did adjust his arm slot on Monday; his horizontal release point moved in a good inch or so while his vertical plot remained the same. It’s unlikely that this small adjustment alone facilitated the increase in rise.
Glasnow’s spin direction still floats around 11:50-12:05, much as it did in 2019:
Despite his modestly-modified release point, arm slot and spin direction alone won’t necessarily increase rise, but (in Glasnow’s case), the pieces of the puzzle are falling into place.
Speaking with independent baseball researcher, Jeremy Maschino, he informed me his sources see an improved spin efficiency on Glasnow’s four-seamer; much closer to 98% spin efficiency during his opening day start.
Averaging around 87-90% spin efficiency in 2019 meant that Glasnow’s four-seamer had an element of cut to it, which can limit run as well as rise. A perfect efficiency under Glasnow’s mechanics and pitch design set the table for more lift.
Here’s a visual on both designs using Baseball Cloud’s BallR tool:
So how does this all fit together? In a vacuum, a 12:00 four-seam fastball is designed/aspires to move straight towards its velocity vector in two dimensions. Given that Glasnow has a slightly more upright release point and his spin efficiency directs the gyro orientation to an almost perfect perpendicular orientation to home plate, it allows the physics of Magnus force (which is what we calibrate with spin efficiency) to act on it in the most effective way possible (more rise/lift).
Now, an extra inch and a half doesn’t seem like much but looking at this chart (via Driveline Baseball) we see that it can, depending on swing path and pitch trajectory, potentially change barreled contact into a pop fly or foul. Or, turn potential contact into a whiff; see below (5cm = ~2″)
This also affects the performance of his (12-6) curveball as well; getting that extra lift can help create a better tunnel for his four-seam to play off the curve (or vice versa), especially with that extra ‘hop’ he gets:
Yes, its just one start for Glasnow, and we are not even a week into the 2020 season. With a well-above-average BU score, adjusted arm slot, and a more Magnus-efficient four-seamer, Glasnow might very well be the difference between the Rays making or missing the playoffs in 2020.
It’s worth keeping an eye on this as Glasnow piles up more starts; the young righty already has the makings of a future Cy Young candidate and the fact he seems to be getting better should raise the eyebrows of American League playoff contenders.