 He was born in Saint John, New Brunswick, Canada.Playing at shortstop in his 1904 rookie season for the Red Sox, O'Neill committed six errors during a 13-inning 5-3 loss to the St Louis Browns on May 21 to become the only 20th century Major League player to record six errors in a game.In the midseason he was traded to Washington in the same transaction that brought Kip Selbach to Boston.