[1] Cottrell, a left-handed pitcher, was recommended to Pittsburgh Pirates scout Howard Earl, and after pitcher Deacon Phillippe and scout Billy Murray saw him play,[4] he was signed by Pittsburgh on June 10, 1911, after drawing interest from multiple major league teams, including the Cincinnati Reds and New York Giants.

[2][1] He made his National League debut with the Pirates on June 21 against the Chicago Cubs, entering in the seventh inning with Pittsburgh trailing 7–1.

[5] Pittsburgh released Cottrell in late August, having only pitched in one game, after club management felt he was not experienced enough to stay with the team.

[10] In November 1912, the Philadelphia Athletics put in a waiver claim on Cottrell,[11] after he was mistakenly included on a list of players the Cubs had waived.

[22] In April 1915, he was placed on waivers by Boston due to a limit of 21-players per roster and sold to the New York Yankees after all other National League clubs passed on him.

[23][24] Cottrell made his Yankees debut on May 27 against the Chicago White Sox, pitching 6.1 innings in relief while allowing two earned runs in an 8–2 loss.