Mails started his professional baseball career with the
Seattle Giants of the
Northwestern League in 1914. That season, he pitched 45 innings and had a
win–loss record of 2–2. In 1915, he pitched 348 innings and went 24–18. Mails joined the
National League's Brooklyn Robins and made his major league debut in September. He pitched two games in relief for the Robins that season, going 0–1. In 1916, Mails pitched 11 games in relief for Brooklyn, going 0–1. The Robins won the pennant, but Mails did not appear in the
1916 World Series, which they lost. In 1917, Mails joined the
Portland Beavers of the Pacific Coast League, pitched 49 innings, and went 3–2. He served in the U.S. military during
World War I and did not play professional baseball in 1918. In 1919, Mails split time between the PCL's
Seattle Rainiers and
Sacramento Senators. Overall, he pitched 301 innings and went 19–17. In 1920, he pitched 292.2 innings for the Senators, going 18–17 with a 3.23
earned run average. In August, Sacramento traded Mails to the
American League's Cleveland Indians. For the rest of the season, he pitched 63.1 innings, going 7–0 with a 1.85 ERA. He helped the Indians win the AL pennant. In Game 3 of the 1920 World Series, Mails pitched 6.2 innings of relief, allowing no runs. In Game 6, he pitched a 1–0 shutout, and the Indians won the series in seven games. In 1921, Mails pitched 194.1 innings, going 14–8 with a 3.94 ERA. In 1922, he pitched 104 innings, going 4–7 with a 5.28 ERA. That December, the Indians sold him to the PCL's
Oakland Oaks. In 1923, Mails pitched 356 innings, going 23–18 with a 2.96 ERA. In 1924, he pitched 382 innings, going 24–22 with a 3.72 ERA. That December, the Oaks traded him to the NL's St. Louis Cardinals. In 1925, Mails pitched 131 innings, going 7–7 with a 4.60 ERA. In April 1926, he pitched in one game for the Cardinals and took the loss. That was his final major league appearance. The Cardinals eventually won the
1926 World Series. Mails spent the rest of the season with the
International League's
Syracuse Stars and the PCL's
San Francisco Seals. For the Stars, he pitched 44 innings, going 1–2 with a 4.50 ERA. For the Seals, he pitched 176 innings, going 9–13 with a 4.19 ERA. Mails played for the Seals from 1927 to 1929. In 1927, he pitched 217 innings, going 11–11 with a 4.40 ERA. In 1928, he pitched 277 innings, going 20–12 with a 3.96 ERA. In 1929, he pitched 250 innings, going 15–16 with a 4.86 ERA. Mails then returned to the PCL's Portland Beavers. In 1930, he pitched 234 innings, going 11–16 with a 4.38 ERA. In 1931, he pitched 212 innings, going 13–13 with a 5.01 ERA. In 1932, Mails played for the
Southern Association's
Chattanooga Lookouts. He pitched 198 innings, going 17–9 with a 4.05 ERA. In 1933, he played for the
American Association's
Kansas City Blues. He pitched 140 innings, going 9–8 with a 3.79 ERA. Mails then returned to the PCL's San Francisco Seals. In 1934, he pitched 167 innings, going 4–13 with a 4.15 ERA. In 1935, he pitched 41 innings, going 3–1 with a 4.83 ERA. In 1936, he appeared in eight games before retiring from professional baseball. In the major leagues, Mails had 516 innings pitched, a 32–25 record, a 4.10 ERA, a 101
ERA+, and 232
strikeouts. In the minor leagues, he had 3,428.2 innings pitched and a 207–193 record. ==Personality==