Do Release Points Change for Different Pitch Types?
Release points have especially interested me lately. Maybe it’s because I never really thought about the story they might be telling until fairly recently. Using Baseball Savant, I pulled every Four Seam Fastball (FF) and Curveball (CU) that Clayton Kershaw has thrown in 2018. These two pitches are polar opposites when it comes to their releases (with fastballs being throw with backspin and curveballs being spun over the top), and Kershaw throws both very well.
Understanding Release Point
This data includes the x, y, and z coordinates of every pitch at the moment it leaves the pitcher’s hand. The variable release_point_x is how far the pitcher’s hand is laterally from the center of the rubber with values to the pitcher’s left being positive. Sidearm pitchers like Chris Sale will have a greater average release_point_x (3.3 feet in 2018) than more over-the-top pitchers like San Diego’s Joey Lucchessi (2.1 feet in 2018).
Similarly, release_point_z tells us the height of a pitcher’s release in feet above the ground. A submarine pitcher will obviously have a lower average value here than a conventional pitcher. For fun, let’s look at the extreme low (Cimber, 2.1 feet on average in 2018) and the extreme high (Josh Collmenter, 7 feet on average in 2017).
Finally, release_extension is the variable that tells how far from the pitching rubber the ball was at release. This is arguably the most important aspect of the release point (due to its relationship with perceived velocity) and the aspect I’ll be looking at today. Since most broadcasts don’t show side views of pitches, i’m not going to able to make a great gif for this. Let’s use this picture from Google Images (please don’t sue me) showing Tim Lincecum’s extension of 6.9 feet from the rubber.
Notice that Timmy is clearly throwing a fastball here (yes, an 87.6mph fastball). In 2018, the 43 pitches with the greatest extensions were all fastballs! This makes sense, as pitchers like to get behind fastballs to get the most spin and speed. The pitch with the 44th greatest extension so far in 2018 was a Michael Fulmer changeup that ended up in the seats. And this raises an interesting question. Is maximum extension only desirable for fastballs? Judging by the scarcity of off-speed pitches on this season’s extension leaderboard, it’s safe to assume that pitchers don’t extend as far for off-speed pitches as they do for fastballs.
This season, the average fastball was released 6.14 feet from the rubber, while the average curveball was only released 5.70 feet from the rubber. So that’s it. Case closed. Fast pitches have higher extensions than slow pitches.
BUT WAIT! The average changeup this season had an extension of 6.06 feet, very similar to the average fastball! As shown above, extension doesn’t necessarily correlate with high fastball velocity. So for the same reasons that it makes sense for fastballs to have high extensions, it also makes sense for changeups to have high extensions. After all, these pitches are thrown with very similar arm actions with only their grips being different. Well what about sliders, the other true breaking ball? 5.77 feet. Closer to the average curveball extension, just as we expected.
So to recap average extension by pitch in 2018:
4 Seam Fastball: 6.14 feet
Changeup: 6.06 feet
Slider: 5.77 feet
Curveball: 5.70 feet
Information about a pitcher’s release point can be very interesting and informative, and I’ll be exploring some these applications in the next post.
