Sticky Fingers: The Rolling Stones, MLB and the Toronto Blue Jays

MLB recently announced a new policy concerning pitchers’ use of foreign substances on baseballs. Commissioner Rob Manfred stated that new enforcement is needed to address the use of sticky substances that have produced much higher spin rates. What, if any, are the implications for the Toronto Blue Jays?

In the days of yore, music companies released albums on vinyl that people played on a turntable, which rotated at 33 1/3 RPMs. So what is the connection between MLB, spin rates and the Rolling Stones? Yep, the Stones released an album in 1971 entitled Sticky Fingers.

Can’t You Hear Me Knocking?

On June 15, MLB issued a statement from Rob Manfred that contained his conclusion that “new enforcement of foreign substances is needed to level the playing field.” He proclaimed that using these materials “has generally morphed from trying to get a better grip on the ball into something else,” namely increasing the spin rates of pitches. As a result, pitchers have utilized these substances and gained “an unfair competitive advantage that is creating a lack of action and an uneven playing field.” The revised policy will take effect on June 21 and includes ten-game suspensions for pitchers caught with a foreign substance. For more details, please refer to this MLB article.

Before the noted press release, MLB let it be known on June 3 that stricter enforcement of Rules 3.01 and Rule 6.02 (c), which prohibits the use of foreign substances, was on the horizon. Perhaps it is a coincidence, but there was a notable reduction in spin rates starting with games after June 2. Closer to home, Statcast data showed that some Blue Jays pitchers experienced a considerable decrease in spin rates post-June 2. Let’s get into the story.

You Gotta Move

Travis Sawchik has written many excellent articles on the spin rate subject. In 2018, he wrote a piece for Five Thirty-Eight that contains a concise summary of the physics of pitches.

“When a thrown ball departs from a straight path, it’s because the speed of its spin creates a pressure differential. The ball moves toward the direction of lower pressure. In baseball, this phenomenon — known as the Magnus Effect — combines with the orientation of the ball’s spin axis to force a curveball to break downward and a slider to move more laterally. More spin equals more movement. The Magnus Effect forces a four-seam fastball in another direction: up.”

Sawchik featured Trevor Bauer in the 2018 article. Bauer observed that “to increase spin on four-seam fastballs, the pitcher’s fingers must maintain contact longer to form a more acute tangential angle with the ball.” Thus, the purpose of applying a sticky substance helps the fingers “adhere to the ball for a fraction of a second longer,” which increases the spin rate and thereby creates more movement.

Driveline Baseball, according to Sawchik, concluded that it “was nearly impossible to increase rpm/mph ratios for fastballs without more velocity or sticky stuff. They determined pitchers have natural rpm/mph fastball signatures that are constant with velocity change.” Driveline named the rpm/mph ratio the “Bauer Unit” after Bauer, Driveline’s first MLB client.

According to University of Illinois physics professor Alan Nathan, an MLB consultant, “it’s probably pretty hard to change that [fastball spin] ratio for an individual.” Nathan did say that a pitcher could naturally change a curveball’s spin rate. However, to do so requires finesse; a fastball needs much less finesse.

Sway

Sawchik experimented to determine the impact of various substances on spin rates. With the assistance of Spencer Curran, a college pitcher from Seton Hall, Sawchik recorded the results below. The impact that different materials had upon spin rates and Bauer Units is striking. Thus, one can see why MLB is concerned about foreign substances, particularly Firm Grip and Spider Tack.