The State of Baseball Aerodynamics: Post 47

The State of the Baseball Aerodynamics is Strong!

Sorry, always have wanted to do that.

I’ve been at this for about 14 months. I thought this would be a good time to provide a (hopefully) concise summary of what we have learned.

Seam Effects on Pitch Break

I nearly said “on lift,” forgetting I am not at work.

Seam Shifted Wake on Doug Neal’s ball signed by 3 hall of famers! The wake is tilted up indicating that the ball is being pushed down due to the early boundary layer separation point on the top of the ball.

Our major finding this year can be summarized as:


Seams can cause two pitches with identical initial trajectory, spin and axis go to different places. If you are a pitcher and want additional break, there is extra break out there to be had. Some of it is easier to harness than others.

“Seam Shifted Wakes” can produce huge break. As evidence, I offer these two pitches that I made at the WSU Sports Science Lab. They were launched identically in terms of spin rate, axis and trajectory. The first video shows a shows a 4-seam baseline pitch.

The second video is a 2-seam pitch with a seam shifted orientation. The difference is quite stark with a force upward and to the right.

Here’s a comparison between two similar sinkers in a game. Left is M. Stroman, right is Trevor Bauer. Both of these pitches have a lot of tilt and therefore run to the right. Notice how Bauer’s also explodes upwards to the surprise of his catcher.

Should you try to throw that? If you are a pitcher, my guess is that you have thrown it, by mistake, and were not able to do it again. I hear that a lot. In fact, Trevor told me he was ill on the night he threw this pitch, and that he threw more than one of them that night. Similarly, Eric O’Flaherty told me of a night that he struck out the side with bases loaded and no one out on a night he didn’t feel fit to pitch. He called his pitch that night an “air cutter” and said it happens when he cannot fully extend.

Even looking at my video, I could not predict which way this pitch would break. I would have guessed down and to the right and would have been half correct.

The point is these are difficult to throw and we don’t yet know enough about them to predict/repeat their behavior (I was able to repeat the pitch with a cannon using the same baseball).

We know they need to be 2-seam, but a special breed of 2-seam. The “horseshoe” needs to spin in a position where it can cause boundary layer separation early on that side. That seems to require gyro, although we have found orientations that have a small effect without gyro.

Here’s the fun thing: if you have that on one side of the ball, you are close to having it on the opposite side too. So small changes can shift it from one side to the other.

That’s hard. It’s probably worth it. But I’ve found lower hanging fruit. I call it a “Scuffball,” but a friend has suggested the BS Pitch, for “Bluff Scuff”. I’m open to other ideas, but let me clear this up: THE BALL IS NOT SCUFFED, it just behaves like it is.

The BS Pitch

You can read about this pitch in Post 45.

I made a stab at explaining how to throw it in that post, but, if you have ever seen me throw a ball, you know better than listen to about that. Trevor Bauer suggested this to mark a ball and reveal if the ball is spinning on a seam.

From the pitcher or hitter’s perspective, that circle should form a line on the side of the ball with a scuff. The ball should move the other direction about 4″ over 55 feet at 90 mph. That 4″ is on top of whatever Magnus would do. The effects are independent of one another.

An important feature of this pitch is that it does not require gyro. In fact, I doubt it will work with gryo as that will move the pole, where the scuff is, away from the hemisphere line of the ball.

As a result, I think this is a good candidate for additional break on any high-efficiency pitch.

I especially like its potential for a “discoball” changeup. My hand calculations indicate that the break the scuff will induce is similar to what Strasburg gets on his changeup from a seam shifted wake. If your change has gyro, maybe SSW is for you. If not, try BS.

Where to from here?

Most of our work has been aimed at mapping the direction to go. I frequently get the question “what range of orientations will give me this effect?” We have not had the time or resources to fully map out how to make these pitches work for you. I believe it could be done and it is my hope that someone decides to make it happen. I’d be happy to discuss what it would take.

Baseball Drag

Our other major findings this year pertained to drag on an MLB ball. We learned that seam height can impact the portion of the ball’s rotation for which the seams cause a very large wake. While the Home Run Committee concluded that the seam height was a minor player in the total drag changes they were seeing, I have two thoughts:

  1. There measurements may have had scatter due to the short flight of the balls during testing, and this scatter may obscure the impact of seam height or
  2. As the committee concluded, some other parameter is the cause. This could be the shape of the seam (how “steep” it is) or the roundness of the ball, an idea I’ve come around to after initially disparaging it.

Why I still think it’s all about seam height

If I hand you a 2019 regular season ball and a 2018 ball and ask you to give me the one with the lower seams, even without looking, you’ll give me the 2019 ball. It’s a really obvious difference. In 2019, we had a year that had the lowest drag AND the lowest seams. That correlation is pretty hard to ignore. We have a plan for a study to answer questions about what is important using printed baseballs with different seam shapes and roundness, but this work is currently not funded.

Conclusion and Thanks

It’s been a really great year. Our measurements are more or less shut down as we wind up and seek funding for next year. I want to thank several people for the support that made it happen:

First, my students. Andrew Smith has done the bulk of the measurements to date and is writing journal papers and a thesis on the Seam Shifted Wake. He is a smart guy, pretty funny and is looking for a job. He’ll get his MSME Spring or Summer.

Nazmus Sakib worked the kinks out of our PIV system and put us on the road. He is in the throes of his PhD on measuring pressure from PIV data, which makes my head hurt.

And John Garrett helped out and took the data for the BS Pitch. He is interested in pursuing an MSME at USU on this project, pending new funding.

Lloyd Smith and the WSU Sports Science Lab funded Andrew Smith and lent us the excellent cannon (which I cannot say enough about).

Alan Nathan has been a great source of help and has introduced me to a lot of helpful people.

Mike Fast gave us the baseballs. We’ve needed them. He’s also been a great source of help.

Driveline visited us early on and has been very helpful. Thanks especially to Kyle Boddy, Eric Jaggers, and Dean Jackson who I’ve continued to interact with.

Rob Friedman has been a great friend, collaborator, supporter and cheerleader.

Michael Augustine and Tom Tango have very patiently straightened me out on many items. Michael Ressler has recently been a big help.

And a bunch of people who I have met more recently, too many to name.

This is the most fun I have ever had at work. Here’s to baseball!

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