Adam Wainwright, One-seam Sinkers, and Seam-shifted Wake

In episode three of a new podcast called Toeing the Slab that aired on October 28, Adam Wainwright appeared as a guest to discuss a number of topics, ranging from farming to a 2021 World Series preview to Wainwright’s thoughts on the Cardinals’ new manager. One of the topics that came up was the use of analytics to help optimize a player’s pitching repertoire (this section begins at around 12 minutes in the video in the link above). Wainwright said he had some reluctance at first to invest heavily in the new technologies, and it’s hard to blame him after putting together such a successful career. But as Weaver said, “It’s what you learn after you know it all that counts.” So, going into the 2021 season, Wainright worked more closely with both Mike Maddux and Cardinals pitching strategist Dusty Blake to try to increase the vertical movement on some of his pitches. Their approach merged a classic style of pitching coach feedback from Maddux with the data-driven commentary provided by Blake. This led to Wainwright’s adoption of a one-seam sinker in 2021, which boosted the variety of Wainwright’s approaches against hitters. In the podcast he mentioned he was more comfortable doubling and tripling up on fastballs because his cutter, four-seamer, and one-seam pitches all had different movement and were harder to square up despite possessing below-average fastball velocities. The Baseball Savant data actually seems to contradict that sentiment, as the vertical movement on Wainwright’s sinker looked to decrease in 2021 compared to 2019, sitting mostly even with Wainwright’s 2021 four-seamer. Regardless, Wainwright thew 861 sinkers in 2021 and didn’t give up a single home run on the pitch, so whether it’s some kind of placebo effect or truly a better pitch in some way, he’s getting results with it.

The one-seam sinker seems to be gaining steam, with a number of struggling pitchers such as the Orioles’ Dillon Tate and the Rangers’ Taylor Hearn adopting the grip in an effort to produce more ground balls. That being said, the grip has been used since at least as early as Mel Stottlemyre’s tenure as pitching coach for the Yankees, where he taught David Cone the one-seam grip. It wouldn’t be surprising to learn that Stottlemyre himself used the grip in his playing days since his sinker was among the best in the league, but outside of a piece on SABR’s website hinting at him playing with pitch grips, I haven’t been able to find anything to solidly confirm that he himself used this grip for the pitch.

The one-seam grip isn't the only unorthodox grip for sinkers. Though he hasn’t put up great numbers with the pitch, Royals pitcher Brad Keller’s sinker one of the more interesting sinkers right now. In a segment on MLB Network, Keller broke down how he throws the pitch, which has good arm-side action and pairs nicely with his slider.

(Credit to Mike Bramblett on YouTube for the footage)

Keller’s sinker is also unique in that it benefits from a phenomenon called seam-shifted wake (SSW). This event occurs when a pitch is thrown so that the seams look to form a line on the leading surface of the ball. It causes turbulent airflow around the ball, which disrupts the Magnus force that causes break and leads to unpredictable movement that doesn’t match up with the ball’s spin. (Disclaimer here that I’m not a physicist, so anyone looking form a more detailed description of SSW can find great articles from Driveline and VEB’s old friend Ben Clemens at Fangraphs). Keller’s sinker in 2020 led MLB in effects seen from SSW, and it’s possible that pitchers have tried to tweak grips to take greater advantage of this effect (see Freddy Garcia’s splitter, which breaks to his glove side instead of his arm side). Not all one-seam or unorthodox sinkers will have SSW since it depends on both arm slot and the angle of release in addition to the grip, but it’s been a development that’s getting more attention in the sabermetric community.

Wainwright’s sinker likely doesn’t have SSW associated with it, which is just fine. Though SSW is a fascinating concept and has gained a following, it still seems to be somewhat rare and doesn’t automatically make a pitch better. Wainwright’s development of his new sinker gives him more options to go to and more unpredictability that helps keep hitters on their heels. For a guy who doesn’t have high-velocity on his fastballs, the execution of a more varied mix of pitches is a must and Wainwright showed that in 2021. It’ll be interesting to see if he can repeat the performance in 2022.