Bierbauer jumped Philadelphia's American Association club to join the Players' League
in 1890. When the PL folded, players were supposed to rejoin their previous clubs.
Pittsburgh became known as the Pirates when they swiped Bierbauer from Philadelphia
through a clerical error in 1891. Bierbauer tied a then-ML record with 12 putouts
at 2B in an 1888 game. In 10 years as a regular, he led his league's second basemen
in assists five times.
(ME)
FROM THE BASEBALL CHRONOLOGY
»February 14, 1891: The National Board of Control "reluctantly" awards three disputed players (Lou Bierbauer, Harry Stovey, and Connie Mack) to the National League clubs that signed them despite the prior claims of the AA. Philadelphia (AA), assumed that with the disbanding of the Players League, Bierbauer would return to play with them. They call the signing of the 2B by Pittsburgh a Piratical" move, and the nickname "Pirates" will stick.
»June 6, 1894: Pittsburgh erupts in the 3rd inning against Boston when Jake Stenzel hits two home runs and Denny Lyons and Lou Bierbauer hit one each, setting a major-league record for home runs in an inning next tied in 1930. Pittsburgh hits seven home runs in all in its 27–11 win.