What is a Seam-Shifted Wake Pitch

In baseball, the Seam-Shifted Wake Effect is a fascinating force that changes how a pitch moves mid-air. Prior to the 2020 season, there wasn’t much large-scale evidence to support the theoretical discussions around this unexpected break in a ball’s movement. There was a lot of debate on whether any pitch-tracking technology could reliably compare a pitch’s expected trajectory based on spin and velocity parameters at release with its actual path. Then came Hawk-Eye—the tracking system adopted by MLB in 2020. This advanced technology now provides data points that allow us to answer questions about how pitches may shift shape on the way to home plate. With this projected vs. actual movement, we’re uncovering insights that could potentially change pitch design, arsenal optimization, and evaluation strategies for the game.

For instance, let’s look at the sinker, a pitch that has somewhat faded from the baseball landscape in recent years. Thanks to Hawk-Eye’s tracking system, we now know that sinkers can utilize the Seam-Shifted Wake Effect to achieve unique motion that traditional pitch-tracking technology couldn’t capture. This unexpected break happens when seams and smooth surfaces on a ball interact with the air differently, altering the pitch’s path to the plate. This new understanding shows incredible potential for changing how pitchers approach arsenal optimization and refine their pitch design to maximize performance on the field.

THE EFFECT ON SINKERS

When it comes to baseball, most pitches that utilize Seam-Shifted Wakes focus on sinkers and two-seamers. This is because these pitch types typically move armside and are the best at creating a pronounced Seam-Shifted Wake effect. The logical choice to start with sinkers makes sense, as they are an established part of the game and their public-facing data allows for easy analysis. A deep dive into SSW gives us a jumping-off point to corroborate existing studies on how gyrospin and spin vectors affect pitches in flight. With access to more MLB data, especially on spin and Spin Efficiency, we could better understand how breaking balls, such as sliders and changeups, work within this context.

Since spin-based measurements are difficult to acquire for certain secondary pitches due to roadblocks like sub 100% efficiency and conversion of gyro to transverse spin, focusing on sinkers offers an ideal study for isolating the effect. Because sinkers are closer to 100% efficiency, their Spin Axis remains stable, unlike other types where descent and transverse components cause movement to the gloveside rather than arm-side. This isolation helps us understand the Seam-Shifted Wake effect on a relative level and explore further analysis that could impact pitch design in the future.

The History

In the world of baseball, pitch movement has fascinated fans and experts alike, including Dr. Alan Nathan from the University of Illinois, who has published numerous articles on his website titled The Physics of Baseball. I remember reading an article of his, in which he broke down how a pitched baseball’s movement pattern is influenced by various forces, and the topic instantly hooked me. As a big fan of the game, I felt compelled to explore this concept further, especially when I came across the story of Yankee pitcher Freddy Garcia.

On April 29, 2011, during a game between the Blue Jays and New York Yankees, Garcia threw a split-fingered fastball that defied expectations. This pitch was captured in slow-motion video, allowing us to observe details like spin rate and the tilt axis of the ball. Even Dr. Nathan was intrigued; the ball’s movement didn’t behave as expected, and this sparked a new discussion on how stitching and airflow around a baseball could impact its flight path. Years before, in 2006, Dr. Rod Cross from the Department of Physics at the University of Sydney had published an article titled Aerodynamics in the Classroom and at the Ballpark, examining how cricket balls move. His insights on stitching effects started applying to baseball, as both sports use balls with seams to influence airflow.

Fast forward to January 2012. Dr. Cross and Dr. Nathan teamed up to analyze Garcia’s pitch further. Dr. Cross even made a video showing how a smooth patch on one side of a baseball could create a unique movement, beyond what Magnus Force alone could achieve. This video was an excellent summary of what he believed was happening, but many were skeptical. After all, without extensive laboratory testing, it was hard to believe a ball with figure-eight stitching could really congregate the seams on one side. But in recent years, Dr. Barton Smith and his colleagues at Utah State University performed laboratory research that confirmed this movement pattern. Through their work, they demonstrated how air flows differently over the smooth and rough surfaces of the baseball during flight, giving rise to the phenomenon known as Seam-Shifted Wake.

Today, Seam-Shifted Wake is recognized as a distinct force, separate from Magnus Force, and it can even become the dominant force on a pitch in certain cases. Dr. Smith’s research on this topic has been groundbreaking, and he has a website you can access for more details and an image of how this looks in action, courtesy of baseballaero.com. It’s incredible to think that what started as simple observations has now changed how we understand baseball’s movement patterns.

How do you Throw an SSW Pitch?

To throw a Seam-Shifted Wake (SSW) pitch, you need to focus on creating a smooth patch on one side of the baseball and aligning the stitching in such a way that it congregates on a different side. This setup is crucial for generating the Seam-Shifted Wake effect. Let’s take the 2-seam fastball as an example—this is the pitch most commonly associated with the SSW effect. To achieve the desired movement, there are a few essential elements you need to keep in mind while throwing an effective 2-seam fastball.

The first element is grip. Place two fingers close to the two seams of the ball, positioning them so they’re facing the pitcher. This grip is important for creating a smooth, white patch on one side of the ball, which should remain facing the batter or catcher at all times. In a tweet by Pitching Ninja, a well-known baseball analyst, the grips of pitcher Kyle Hendricks are shown to highlight how to hold a Seam-Shifted Wake pitch. Kyle Hendricks, who is famous for his 87mph Two Seamer, uses this grip, ensuring the release and spin create an ideal SSW effect. The tweet mentions that Braun’s zombie bat even attempts revenge on the ball—an inside joke about how the pitch is so effective that it almost seems to “break” the bat.

This smooth white patch is critical as it influences how the ball moves during flight. According to Dr. Cross, who explained the Seam-Shifted Wake effect in a video, having one side of the ball smooth while the other has seams makes the air movement around the ball different. As the ball is thrown with backspin, it rotates along an axis that is perpendicular to the seams. This creates the unique Seam-Shifted Wake movement by forcing the ball to move in a way that defies typical expectations.

When you watch the airflow around the ball, you’ll see that the air sticks to the side with seams longer than the smooth side, which causes deflection. This movement is different from what you’d expect if it were purely a Magnus Force-based pitch. In baseball, this effect allows for more complex movement profiles. The side with stitching creates turbulent airflow, while the smooth side allows the ball to move more freely.

Baseball pitchers like Kyle Hendricks and Freddy Garcia have shown how effective this technique can be. By mastering the Seam-Shifted Wake, a pitcher can confuse batters and gain a competitive edge. In the past, pitchers used methods like spitballs and scuffballs to achieve similar effects, but SSW does this naturally by orienting the seams to create unique movement.

In short, the Seam-Shifted Wake pitch is about utilizing the seams and smooth surfaces of the baseball to create force on one side. This causes the ball to move unpredictably, making it harder for the batter to anticipate its path. When you perfect the grip and release on a 2-seam fastball, you’re essentially using physics to throw a pitch that has a distinct movement pattern, thanks to the Seam-Shifted Wake effect.

Today’s Technology

In Today’s Game, pitch movement is closely measured using three technologies that capture the nuances of how a seam-shifted wake pitch behaves. These tools—Rapsodo, Trackman, and Hawkeye—are now common in MLB stadiums. Rapsodo units can record the seam-shifted wake of a pitch, showing the way it moves. Meanwhile, Trackman technology can even incorporate the seam-shifted wake into its data, as it reads the movement of the ball in real-time. The Hawkeye system takes it further, capturing both the tilt axis at release and the tilt axis based on the movement of the ball, allowing a clear picture of the pitch’s flight path and a chance to observe which pitcher has benefited most from the Seam-Shifted Wake effect.

Each of these technologies provides detailed data on the pitch and its trajectory, helping us understand the unique movements that aren’t explained by traditional metrics alone. By comparing observed changes in Today’s Game, these systems can highlight subtle variations in pitch movement—especially when the pitcher intentionally leverages the Seam-Shifted Wake to create late or unexpected movement on the ball.

How is it observed in Today’s Game?

One of the easiest ways to see the effect of a seam-shifted wake in action is by studying the tilt axis of pitches using MLB’s advanced Hawkeye data on Baseball Savant. In particular, Baseball Savant provides insights into the difference between what’s known as observed-movement and spin-based movement. As it follows, observed movement represents the actual movement of the pitch based on its plate location and initial velocity vector during flight. On the other hand, spin-based movement shows the initial path from release to home based on the pitch’s tilt axis.

By analyzing the chart of tilt axes from a pitcher’s view, Baseball Savant translates this data into degrees, starting at 12:00 as 0 degrees. This reveals how pitchers have a difference in observed and spin-based movement, often even if it’s intentional or not. For example, with a 2-seam fastball, the Seam-Shifted Wake introduces subtle changes, allowing each pitcher to add a unique degree of movement that makes their pitch impacting and deceptive. This movement becomes especially important in understanding how pitchers craft their unique styles using the Seam-Shifted Wake concept.

Examples

Seam-Shifted Wake pitches are unique because they can make the ball take surprising paths, thanks to the movement caused by the seams. When I first looked at charts on Baseball Savant from Spencer Turnbull and Kyle Hendricks, two skilled pitchers known for this style, I was fascinated by how specific movement could be linked to seam orientation. In Turnbull’s tilt axes from his last season, there’s a noticeable difference between his spin-based movement and his observed-movement. On his chart, the 4-seam fastball in red tends to move to about 1:00, while the sinker in orange goes toward 3:00. This difference, represented on the left by spin-based and on the right by observed tilt axes, showcases how Seam-Shifted Wake can impact pitch design.

To illustrate, a Twitter post from Eno Sarris in 2020 shows Turnbull’s two-seam overlayed with his seam-shifted wake, where the spin axis makes the pitch veer off in an unexpected direction (see pic.twitter.com/nhvDP0z5QN). This is one of the most interesting examples because it combines spin, orientation, and seam direction in a way that even an experienced pitcher might not expect. Kyle Hendricks offers another great example of this effect. His 2-seam often shows a spin-based movement at about 1:00 on the left for both pitches, but observed-movement reveals a shift. His 4-seam aligns near 1:00, while his sinker drifts toward 2:30, a difference that changes how these pitches behave in flight.

This new development in pitch design is opening doors for pitchers to rethink their strategies. At RPP Data Analytics, Intern Ken Ruth, a computer science student at Brigham Young University, has explored how Seam-Shifted Wake pitches can bring unexpected success. Studying data analytics with the BYU Baseball program, he’s part of a team that is likely to keep researching these pitches, potentially influencing how Seam-Shifted Wake impacts pitchers for years to come.

CONCLUSION 

As we continue scratching the surface with sinkers, it’s becoming clear that other pitch types like changeups and sliders deserve a closer look. If MLB were to release spin vectors publicly, we could measure metrics like spin efficiency and spin-based movement directly, which would open up more in-depth research on sliders. For now, we plan to conduct an investigation on the one-seam sinker at our facility to attempt understanding if different pitch grips or orientations within this family can hack the SSW effect. Our hypothesis suggests that sinkers in the one-seamer family, or those similar to the Laminar Express pitches, might be more prone to take advantage of this effect.

F&Q

Who discovered the seam-shifted wake?

The seam-shifted wake phenomenon was coined as a term in 2019 by Andrew Smith during his work on it with Barton L. Smith (no relation) at Utah State University (USU). Nazmus Sakib and John Garrett also contributed to the early work on this discovery.

What are the seams on a baseball?

The seams on a baseball are formed by one seam, but the curvature of it in its pattern around the ball allows the pitcher to present different aspects of the ball seam, thereby affecting the aerodynamic performance in flight.

Why is it called a 2 seam fastball?

It’s called a 2-seam fastball because, as the ball comes off your hand, you’re going to see two seams spinning. The way it spins, you’ll see two seams, you see two seams, you see two seams.