 On May 1, 1951, Gumpert became part of baseball history when he allowed Mickey Mantle's first home run, during a relief appearance at Comiskey Park.His value improved by his All-Star selection, Gumpert was traded that offseason, on November 13, 1951, along with outfielder Don Lenhardt to the Boston Red Sox for infielder Mel Hoderlein and pitcher Chuck Stobbs.After getting into ten games for the Red Sox, with one start, he was traded again on June 10, this time to the Washington Senators with fellow hurler Walt Masterson for Sid Hudson, another right-hander.