The Detroit Tigers and Seam-Shifted Wake

There’s a new concept in pitch design dealing with Seam-Shifted Wake, and the Detroit Tigers have a great chance to get in on it early.

My six-year-old doesn’t particularly care about my thoughts on Detroit Tigers roster construction, let alone something as obscure as seam-shifted wake, so when we go for walks our conversations tend to veer toward the natural world. Last week he asked me why geese fly in a V formation.

A quick YouTube video later and I had an easy answer. When a goose flaps its wings it creates a vortex of air. Directly behind the goose the air is pushing straight down, but the air swirls back up on either side of that so-called downwash. So when other geese fly to the rear and side of the front goose they actually get a slight upward boost. Hooray for science!

Now, if you’re like me, you don’t spend a lot of time thinking about fluid dynamics. Sure, you may angrily shake your first at the sky when a gust of wind topples your lawn furniture, or perhaps you sold some Non-Newtonian fluids in college to make ends meet, but you’re probably not sitting around pondering laminar flow.

But fluid dynamics plays a huge role in baseball, particularly with regard to pitching. Recent research by Dr. Barton Smith and his team at Utah State University may lead us into the next frontier of pitch design, and the Detroit Tigers have a chance to be at the forefront of this new movement.

What is Seam-Shifted Wake?

Driveline Baseball wrote a terrific, in-depth article on seam-shifted wake, and their explanation is better than anything I can produce:

"What makes a baseball so unique is the presence of seams in conjunction with smooth surfaces on the ball itself, potentially allowing for specific grips of the ball to create different movement profiles…the main concept to grasp is that when you break the symmetry of a wake (creating turbulence on one side), you can create force, and thus movement, that isn’t typical. This can be achieved through seam orientation, hence a “Seam-Shifted Wake”."

For most of baseball history pitchers understood how gravity and spin affected the movement of baseballs. They didn’t need any physics classes, they simply knew a thrown baseball would eventually fall to the ground, and adding spin could make it move in different directions. And certainly some pitchers realized the way they held the ball could affect its movement.

It wasn’t until the last decade or so that we could directly measure things like spin rate and how it plays into pitch movement. We’re still in the middle of this awakening, but the introduction of Hawk-Eye pitch tracking in 2020 finally gave observers the chance to directly measure spin axis, which then provided enough data points to prove the substantial impact seam-shifted wake has on pitch movement.

For our purposes we just need to know seam-shifted wake is real, and quite impactful, particularly for pitches like sinkers and changeups that tend to show arm-side movement.

In fact, when Driveline looked into real-world run values based on five movement factors, seam-shifted wake had the second biggest impact. It wasn’t as important as vertical break, but it made a bigger difference than horizontal break, arm angle, and even velocity.

This post is already deeply nerdy and I haven’t really gotten into the details. If you want to learn more I suggest reading that Driveline article, or this piece at Baseball Prospectus, or various articles by Dr. Smith at Baseball Aerodynamics.

How Might Seam-Shifted Wake Affect the Detroit Tigers?

You may remember the Detroit Tigers recently hired Chris Fetter. Fetter is a modern pitching coach who loves getting into the weeds in terms of pitch design. You can hear him talking about it on this Rhapsodo Podcast from September, and how important it is to help pitchers maximize their potential. This sort of thing is his jam.

Do the Detroit Tigers have pitchers who throw sinkers and have seemingly failed to maximize their potential? Why yes, yes they do. Driveline lists Bryan Garcia as one of the MLB pitchers whose seam-shifted wake actually produced less movement than expected. There are six other presumed members of Detroit’s 2021 pitching staff who threw sinkers at least 20% of the time last year.

Movement from seam-shifted wake isn’t some panacea. Chris Fetter won’t snap his fingers and turn Michael Fulmer into Roy Halladay. But most pitch design thus far has seemingly followed the Houston Astros model, with teams trying to maximize vertical movement by focusing on pitchers tunneling breaking balls and high-spin fastballs at the top of the zone.

The problem with that model is spin rate is an innate thing that can’t really be improved (unless you cheat). Guys with low spin rates were kind of out of luck.

But movement caused by seam-shifted wake means those sinkerballers have an impactful way to improve and maximize their potential. By changing the orientation of the seams, pitchers can now measure and improve the movement on their offerings.

And make no mistake, this is already happening. The team that threw the most sinkers in 2020 and had the lowest xwOBA on sinkers? The Los Angeles Dodgers.

The good news here is that the Dodgers ranked 27th in the percentage of sinkers thrown in 2019. That suggests they just learned how to maximize seam-shifted wake in the past year, which means, at least in this regard, the Detroit Tigers are probably only a year behind the best franchise in baseball.

The first goose in the formation does most of the heavy lifting, but it also gets to decide where the birds are headed. If Chris Fetter can get the Detroit Tigers to take advantage of seam-shifted wake quickly enough, then their flock of young pitchers might soon be able to lead the way on this new pitch-design frontier.