He was a left-handed pitcher over parts of 14 seasons (1917–1921, 1924–1932) with the St. Louis Cardinals, Cincinnati Reds and Chicago Cubs.

For his career, he compiled a 72–95 record in 410 appearances, most as a relief pitcher, with a 3.88 earned run average and 765 strikeouts.

May won 35 games for the Vernon Tigers in 1922, breaking Cack Henley's record for wins in a Pacific Coast League season.

[1] May was a member of the National League pennant-winning 1932 Cubs, suffering the loss in the fourth and final game of the 1932 World Series against the New York Yankees.

In World Series play, he had a 0–1 record in two appearances, with an 11.57 earned run average and 4 strikeouts.