Complex sentence: The St. Louis Cardinals, a Major League baseball (MLB) franchise based in St. Louis, Missouri, have competed in the National League (NL) since 1892, and in the American Assocation (AA) from 1882 to 1891.
Split into simpler sentences: The St. Louis Cardinals, a Major League baseball (MLB) franchise based in St. Louis, Missouri, have competed in the National League (NL) since 1892. Prior to the NL, they also played in the American Assocation (AA) from 1882 to 1891.