Yermín Mercedes is the first #WhiteSox player to homer off a position player pitcher since Minnie Miñoso off Bobby Kline on August 27, 1955
— Christopher Kamka (@ckamka) May 18, 2021
J.C. Martin homered off Willie Smith on May 10, 1964 but Smith was a 2-way player (15 pitching appearances that season)