An Initial Encounter with Pitch Design
Earlier this fall, we at Cal Poly Baseball acquired a Rapsodo unit to use during bullpen sessions.
Our first discovery dealt with a Freshman pitcher and his breaking balls. During a routine bullpen, multiple coaches noted the similarity between his Slider and his Curveball. For the first time, we were able to check the accuracy of this observation with the data.
Unsurprisingly, they were right. The two pitches had very similar movement profiles, as seen here:
The overlap between the Sliders and the Curveballs is cause for concern, as usually, unless there is a large velocity difference like with a Fastball and Changeup, it doesn’t make much sense for a pitcher to have two similarly moving pitches when one would have the same effect.
Let’s take a look at the two pitches:
The Slider
The average characteristics of this pitch:
Velocity: 72–78
Horizontal Movement: 0 to -12 inches
Vertical Movement: -5 to -7 inches
Spin Efficiency: 25–50% (0% is generally optimal for a Slider)
Spin Axis: 7:00 to 8:00
The Curveball
The average characteristics of this pitch:
Velocity: 73–78
Horizontal Movement: -4 to -10 inches
Vertical Movement: -6 to -12 inches
Spin Efficiency: 30–60% (100% is generally optimal for a Curveball)
Spin Axis: Between 6:30 and 7:30
Although they clearly aren’t identical, I would call them a little too close for comfort. So what now?
The Solution (?)
To search for some sort of precedent, I went to Baseball Savant’s new Pitch Arsenals tool and let it cycle through until I found a major leaguer with overlap on the movement of his Slider and Curveball (which was about as hard as you might imagine). I came across Jakob Junis:
To check out his release and how it may help our pitcher with his breaking ball, I searched for Junis on Pitching Ninja’s twitter feed…and struck gold.
And much to my delight…
…the hand positions at release are nearly identical. In fact, Junis’ Slider seemed to be somewhat of a regular feature on the Cosmic Hub of Pitching Gifs. It turns out, the pitch was worth 4.2 runs for Junis in 2018. If he can do that with his slider, maybe we can develop a quality breaking ball in its image.
On a darker note, let’s check out the Curveball comparison. It’s a pitch that you won’t find next to Junis’ name on a “nasty” gif. He throws it only 8% of the time (compared to 33% Sliders) and it was worth negative value last season. For better or for worse, here is his Curveball release compared to that of our own pitcher’s:
It may be a bit tough to see here, but the arm slot and the grip itself are different. Which makes sense, as this isn’t the same pitcher after all. But according to all prior evidence, neither is doing much good.
Conclusion
So in a vaccuum, after examining this isolated example, one may advocate for our Cal Poly Freshman to focus on developing his Slider (possibly modeling it after Junis’ or another MLBer with a similar arm angle, pitching profile, etc.) and ditch the Curve. And that may not be a bad idea. But it’s something that’s much easier said than done. What will come next for our pitch design effort is the hard part, but we look forward to the challenge.
