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Trevor Rosenthal threw the best changeup you’ll ever see

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Milwaukee Brewers v St Louis Cardinals
High-sock Rosey is the best kind of Rosey.
Photo by Dilip Vishwanat/Getty Images

On May 7th, 2017, St. Louis Cardinals relief pitcher Trevor Rosenthal threw only one changeup against the Atlanta Braves. He certainly made the most of that one pitch, though, as it is probably the best changeup you’ll ever see. Yes, you read that sentence correctly. I am confident enough to put it in writing that the strike-three changeup to Kurt Suzuki should become the featured changeup of a yet-to-be-created changeup instructional video — particularly when you take into account Rosenthal’s utilization of pitch sequencing. Do those videos even exist, you ask? Well, Adam Wainwright made a curveball video for MLB.com, so I don’t see why a changeup one couldn’t also be created.

First, for some perspective: in my time with Viva El Birdos (my first post was way back on January 7, 2014), I have written at least 100 posts centered on the changeup — my undisputed favorite pitch. Now, that is not at all meant to serve as an indirect way of claiming to be a changeup “expert” — that title rightfully belongs to either Eno Sarris or Harry Pavlidis — but I am not embarrassed to admit that I have spent an accumulation of at least a few days (probably even up to a week now, honestly) watching GIFs and sifting through PitchF/x data on changeups and changeups, alone. All that being said, courtesy of BrooksBaseball.net, here are some of the PitchF/x-related specifics regarding Rosenthal’s changeup to the Braves catcher:

Trevor Rosenthal changeup to Kurt Suzuki (May 7th, 2017)

Velocity Dragless Horizontal Movement Pitch Prior Fourseamer Velocity Velocity Differential Result
Velocity Dragless Horizontal Movement Pitch Prior Fourseamer Velocity Velocity Differential Result
89.2 MPH -11.46 inches Fourseamer 99.9 MPH 10.7 MPH Whiff

While I consistently rave about a changeup’s flight — namely, how much arm-side run it gets — the first, and most important, feature of the pitch is velocity. No, not velocity in terms of overpowering hitters — even though Rosenthal’s changeup is as fast or faster than many pitchers’ fourseamers — but rather the pitch’s velocity differential. When thrown from an identical release point with similar arm speed and action, the velocity differential between a pitcher’s changeup and fourseamer is what leads to off-balance swings, weak contact, or often, no contact at all.

The ability to attain a plus-10 velocity differential on an 89.2 MPH pitch shouldn’t be legal, and yet, Rosenthal did just this to Suzuki (10.7 MPH differential) and has somehow nearly averaged this feat thus far in 2017 (9.95 MPH differential at the time of publishing). Sure, a plus-10 velocity differential isn’t all that impressive when the changeup is thrown in the high-70’s/low-80’s, but it certainly is when thrown in the high-80’s/low-90’s.

The next thing to consider is dragless horizontal movement (found in the “Scatter Charts” tab of a pitcher’s BrooksBaseball.net card). Ideally, a changeup will follow a similar path to the fourseamer, though the velocity and grip differential will naturally lead to more arm-side run. Honestly, a changeup more closely mimics the movement of a sinker, but this doesn’t mean a pitcher must throw a sinker in order to possess an effective changeup (example number one: Rosenthal, Trevor). For those interested in why I use dragless movement over the standard movement readings provided directly in player cards (or even on FanGraphs leaderboards), this primer is for you — written by Alan Nathan, Ph.D., who is so much smarter than me.

If you didn’t feel like reading up on the physics of a moving baseball or are already finished with Nathan’s paper, I am here to inform you that Rosenthal’s changeup to Suzuki exhibited 11.46 inches of dragless horizontal movement — or 1.35 inches more than his 2017 average and 1.71 inches more than his 2016 average. Thus, this “best changeup you’ll ever see” not only accomplished the desired velocity differential (with a higher degree of difficulty, as explained above), but also possessed a significant amount of horizontal movement. The GIFs below, courtesy of the one and only @cardinalsgifs, will help you better visualize the magnitude of the pitch’s movement.

Strikeout of Kurt Suzuki (BrooksBaseball At Bat)

Horizontally, the back-to-back pitches landed roughly 6 inches apart, which, given the sheer size of an MLB strike zone, really isn’t all that much. As you can see, they took very different flight paths to reach their final, previously-determined-to-be-similar location. While the trails do an amazing job providing a visual for the pitches’ movement, let me walk you through a brief exercise as well. Using the tip of home plate as a reference point, Rosenthal’s set-up fourseamer — released to the right of home plate’s tip — never even came close to crossing it, two-dimensionally, of course. Conversely, the put-away changeup — possessing a nearly identical horizontal release point as the fourseamer — started on the right side of the tip of home plate (again, we are thinking two-dimensionally here), crossed over to the left side, before bending back to the right side and eventually being caught by Yadier Molina.

Enough about movement, though, it is time to revisit velocity differential. Suzuki fouled off three fourseamers in this at bat — including the set-up fourseamer pictured above. The average velocity of those three fourseamers? 99.5 MPH. On the set-up fourseamer (99.9 MPH), Suzuki revved up for the pitch — lacing it down the left-field line into the seats for a foul ball. Considering how infrequently Rosenthal throws the changeup — the slider has seemingly taken over as his primary offspeed option — it’s not surprising Suzuki geared up for yet another fourseamer. And, out of the hand, the changeup looked like it could have been another fourseamer as well (hence, the blending of the red to sky blue trail — did I already mention that @cardinalsgifs is amazing?). Unfortunately for Suzuki, the put-away pitch was 10.7 MPH slower — as already mentioned a couple times above — and though he was eventually able to recognize the difference, it was far too late.

Layered version (mainly for your viewing pleasure)

Layered version focusing on Suzuki

Admittedly, it took me quite some time to understand what I was seeing in this GIF. However, I think I was able to find exactly what I was looking for (and am genuinely curious to find out if anyone else notices anything). But, I wanted a way to visualize just how geared up Suzuki was for the fourseamer, after fouling off the 99.9 MPH one down the line. The answer can be found in an identically-timed leg kick followed by the hips, as he throws them open almost simultaneously. Sure, the bat lags behind a bit because he realizes — too late for it to matter — that the pitch is actually a changeup, not a fourseamer.

Bottom line, was it a bit far-fetched to crown Rosenthal’s changeup the “best you’ll ever see”? Absolutely. None of us have the time to watch every single changeup ever thrown. Plus, with this being a Cardinals-based website, it’s not unreasonable to believe that most of our readers spend the majority of their time dedicated to baseball watching the Cardinals. With this technicality in place, my statement doesn’t end up being that far-fetched. Regardless, from a velocity, movement, and sequencing perspective, we can all agree on one thing, the pitch was filthy, and Suzuki never stood a chance.

As always, credit to @cardinalsgifs for the GIFs (follow him on Twitter!) and BrooksBaseball.net for the PitchF/x data used in this post.