Why Identical Movement Doesn’t Mean Identical Pitches

If you've watched any baseball over the past few years, chances are you've heard announcers gush about an offspeed pitch's spin rate or movement. But raw shape and velocity only tell part of the story, and a pitch shape that works for one guy might not work for somebody else.

Why? Because a secondary pitch doesn't exist on it's own: how it moves relative to the fastball that sets it up matters. Two offspeed pitches can have identical movement and still play completely differently, depending on how much that pitch separates from the fastball, and whether that separation is bigger or smaller than typical.

This can be a difficult concept, so here are two case studies from this year's MLB pitch data that illustrate this point.

Case Study 1: "Same" Changeup, Different Results

Bryan Baker (left) and Michael Lorenzen (right) both throw a changeup that averages right around 8-9 inches of induced vertical break and 14-15 inches of arm-side run. In isolation, it's basically the same pitch.

But look at where those changeups start from. Baker's fastball has a lot of carry and perceived cut (19.2" IVB, 3.7" HB). That means his changeup drops 10 inches and runs 11 inches compared to his heater. The green line on the movement plot is the typical separation for a changeup from a fastball in the big leagues. As you can see, Baker's gets significantly more depth and run than average, despite its modest raw movement.

Lorenzen's fastball, by contrast, lives in the "dead zone" (13.8" IVB, 10.2" HB). So, even though his changeup has a similar shape to Baker's, it has far less separation from his fastball, well below league average.

That gap in separation (or lack thereof) shows up in the pitch's performance. Lorenzen's changeup had a 27.5% whiff rate and a 19.1% called-strikes-and-whiff rate. Baker's had a 33.8% whiff rate and generated a called strike or whiff 32.3% of the time, carrying him to a league-leading 41 saves this year. And despite identical movement, Baker's changeup had a run value per 100 pitches 3 runs better than Lorenzen's.

Case Study 2: Different Pitch, Same Movement

Pete Fairbanks (left) throws a slider. Carmen Mlodzinski (right) throws a curveball. Different names on the scoreboard, but strip the labels off and look at the movement: Fairbanks' slider averages -8.5" IVB and 6" HB at 83.8 MPH. Mlodzinski's curveball averages -8.9" IVB and 7.5" HB, also at 83.8 MPH. Tagged differently, but basically the same pitch in terms of "stuff".

What separates them is the fastball they're coming off of. Fairbanks' heater is like Baker's: lots of ride and perceived cut. So his slider drops almost straight down relative to that fastball — over 26 inches of pure vertical separation and only about 7-8 inches of horizontal separation. That's a true north-south look, with far more separation than typical, and it's a big reason Fairbanks got a 39% whiff rate on the pitch.

Mlodzinski's fastball, like Lorenzen's, lives in the "dead zone" (12 inches of carry, 10 inches of arm-side run), so his curveball separates on a shallower, more diagonal line — closer to 21 inches of vertical separation with 17-18 inches of horizontal separation. Its separation is that of a more traditional curveball: down and across, rather than straight down. It's not a bad pitch, but it doesn't provide as unique a look, and the performance shows it, with a whiff rate of under 25% and a run value 1.5 runs worse per 100 pitches than Fairbanks'.

And movement is only part of the picture. Neither case study even gets into release point or approach angle, two more factors that can make pitches with identical movement play completely differently. It's just more proof that optimizing an arsenal is about more than just looking at a pitch's horizontal and vertical break on a movement plot.

How This Applies to You

If you're only looking at your changeup's or breaking ball's raw numbers on a movement plot, you're missing half the evaluation. A pitch doesn't perform in a vacuum: hitters read it based on how it plays off your fastball.

So, if you're trying to build or improve an offspeed pitch, stop benchmarking it against league-average movement and start benchmarking it against your own fastball. The question isn't "is my slider's shape good?" It's "does my slider play well off my fastball?"

And, as we see with both of the case studies, one of the best ways to improve your offspeed stuff is to improve your fastball. Both Baker's changeup and Fairbanks' slider play so well because they have plus fastballs, compared to Mlodzinski and Lorenzen who don't generate ride, sink, cut, or run with their primary fastballs. So if you have an off-speed pitch that looks good on a movement plot, but isn't performing well in game, take a look at your fastball and ask yourself how the secondary pitch plays off of it.

What This Means for Your Training

Optimizing your arsenal as a whole, not just looking at each pitch on its own, is exactly how we structure our pitch design work. We pair your Trackman data with data from hundreds of thousands of pitches thrown in the MLB, MiLB, and college to help you build an arsenal that doesn't just look good on paper but will help you get outs when it matters.

If you're not sure how to optimize your arsenal, or if your pitches play well off each other, we're offering a two-day Masterclass on November 7-8th to help answer those exact questions. Whether that's adding a new pitch, improving one you've already got, or optimizing your fastball profile, you'll leave knowing exactly what to work on to dominate this spring. You'll also get force plate data off the mound, jump data, arm strength and sprint testing, plus a full movement assessment, so you can start the winter with a plan to get stronger, more powerful, and move better on the bump.

Sign Up For the 2-Day PCU Masterclass

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