Cooper parlayed a sensational Texas League season, after which he was hailed as “another Speaker,” into an invitation to join the pennant-bound Giants in 1913. He was voted a full World Series share and showed perverse appreciation by jumping to the outlaw Federal League.
Cooper broke his leg as soon as the Federal League opened its 1914 season. When the Federal League dissolved, Cooper and Bill Bradley retained John M. Ward as an attorney. Ward won a suit for the players, whom he had dealt with earlier as general manager of the BrookFeds, for another “bonus” based on presumed World Series entitlements due had they not jumped legal contracts.
Reinstated, Cooper played two seasons with the Phillies, failing to hit even .200, and returned to Texas.