james 'doc' casey was a third baseman who joined the brooklyn superbas in 1899 and rejoined them in 1906.
casey played in 134 games for brooklyn in 1899, but only appeared in a single game for them the following year, as he had decided to jump to the detroit tigers, who in 1900 were a minor league team. casey stayed with detroit when they entered the major leagues in 1901, but after the 1902 season he left and joined the cubs. after three seasons in chicago, casey was back with brooklyn, playing in a career high 149 games. he closed out his big league career with brooklyn the following year.
i find it interesting that his 1990 target card lists him as an infielder
when he played third base exclusively for the superbas, at least according to baseball reference.
supposedly, casey earned his nickname by providing dental services to his teammates. he may or may not have been a dentist following his baseball career, but did run a pharmacy in detroit until his death in 1936.