A Retrospective Analysis of Major League Baseball Hit-by-Pitch Rates before and after the Crackdown on Foreign Substance Use.

Objective: Determine whether there was an increased incidence of hit-by-pitch events in Major League Baseball (MLB) following the decision to enforce the foreign substance ban for pitchers during the 2021 season.

Design: Descriptive Epidemiological Study.

Setting: Major League Baseball hit-by-pitch data from publicly available Web sites ( mlb.com and fangraphs.com ).

Participants: Major League Baseball players during the 2017, 2018, 2019, 2021, and 2022 seasons.

Independent variables: Hit-by-pitch exposure data by season and individual pitch type.

Main outcome measures: Hit-by-pitch incidence rates from the 2017 to 2019 seasons (preenforcement) and the 2021 to 2022 seasons (postenforcement). Rates were compared with incidence rate ratios (IRRs).

Results: Hit-by-pitch incidence rate increased from 2.66 to 3.06 per 1000 total pitches (IRR, 1.15 [95% CI, 1.08-1.23]; P < 0.0001) following the enforcement. Incidence rates for 2017, 2018, and 2019 did not differ from each other individually, but incidence rate of all 3 seasons individually were significantly lower than that for the 2021 season ( P < 0.005). Sliders were 29% more likely to hit batters following the enforcement ( P = 0.0015).

Conclusions: Major League Baseball batters were hit by pitches at a significantly higher rate following the league's crackdown on foreign substance use for the 2021 seasons compared with the same time of year during the 2017 to 2019 seasons. This was followed by a slight regression toward preenforcement levels during the 2022 season.