We’ve released a new tool in FanGraphs Lab. The Paired Pitches tool is a visualizer that shows how different pitches a pitcher throws together. It measures how much gravity, speed, and motion make each pitch different from a common central location. It’s probably easiest to start with a picture. This is Yoshinobu Yamamoto’s mix as shown in the Paired Pitches tool:
To use the tool, you select a pitcher, select a pitch, and click anywhere on or near the strike zone to get that pitch. The tool then finds every other pitch the pitcher throws relative to that pitch. You can drag any height in the resulting image to move the areas around, and they will always be paired with each other, with the same distribution of relative motion:
If you’re wondering why a hitter might jump over Yamamoto’s slider in the dirt, it’s because its initial trajectory looks like a medium fastball. If you’re wondering why they would take a corner cutter, well, it’s because it looks like a wall slide.
Now for a quick rundown of the math: The way this tool works is to assume that each pitch is released from a different point of release, but it is intended to intersect at one point in the two-dimensional plane of the strike zone if they continue to travel from their point of release to home plate without the effects of spin or gravity. Think of it as where the pitch will “go” if you just draw a straight line where the ball travels as soon as it leaves the pitcher’s hand.
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Simply enough, that idea of measuring motion against an imaginary, non-accelerating world and plotting intersection points at home is exactly how pitch motion math already works. The Paired Pitches tool automatically calculates every pitch as if it were “aimed” at a position that places the anchor pitch wherever you want.
Actually, that is sometimes but not always how pitchers use their pitches. Pitchers pair their other pitches, sometimes, and combine them in different combinations. Take Garrett Crochet. He can pair an in-zone fastball with a diving changeup against righties:
Against lefties, he works on his sinker, turning the pitch into a horizontal nightmare for hitters. His sinker stays inside, his sweeper dives, and he can use a cutter/sink pairing to get calls for strikes in the infield. Similar spaces, paired in different places, have different effects, so you can drag them around the tool and change the anchors:
Now that I’ve shown you how much fun it is to pair fields and think along with pitchers and catchers, it’s time for a few ideas. This short description of how pitches diverge on the way home won’t explain everything about pitching at night. Curveballs, in particular, don’t fit well into this paradigm. Pitchers do not “target” themselves, according to the initial trajectory, in the same place as their fastballs. Curveballs are so slow that they can just fall too far on the way home. Instead, pitchers aim at a higher pitch, which helps explain the distinctive “hump” in the hand that sometimes helps hitters take it.
We don’t claim that this tool captures everything about voice interaction. Pitchers can and do choose pitches based on how they look compared to one another, but they also use many other tactics. They may want to throw the pitch in a completely different trajectory than the previous one to change the hitter’s eye level. They may want to throw a no-contact slider to take advantage of a no-swing strike early in the rotation. But more often than not, they want to pair the fastball with the sweeper away and get hitters to swing at both:
Below, I’ve compiled a list of tips, tricks, and frequently asked questions from initial testing of this tool:
- The sizes of the bubbles are proportional to the variation in movement of each pitch. Pitches with variable motion profiles such as splitters and changeups have large bubbles because their motion is less certain from one pitch to the next. Fastballs tend to have little variation in their movement. You can change the bubbles to baseball size in the settings.
- If a pitch isn’t showing, it’s probably because that pitcher hasn’t pitched enough in the filter/time frame you’re looking at. You can minimize the drop down.
- This tool, and all Lab tools, now have copy and download options. If you want to share your photo, we want to know.
- I think the dividing lines look too sharp, but they can be changed in the settings.
- If you’re using this to think like a pitcher, remember that fastballs are best suited to different pitches depending on where they are.
- Since we calculate many pitch and pitch metrics, we dynamically calculate the vertical pitch angle in the Pitch Metrics tab. It’s a good interactive lesson on how the position of the plates affects their proximity.
- Go check out Nolan McLean’s arsenal. It’s a lot of fun – and this tool explains why he’s had control over his curveball for so long.
Sean and I expect to make feature updates to the Paired Pitches tool in the coming weeks and months. This version was good enough to be released, but we are still developing ours. We also want to hear what improvements you can make, so please give us feedback via the menu that appears on all Lab pages.
