Mack spent three years at Villanova University, then joined the Rockford Forest Citys of the National Association for the 1871 season.

[1] McLean claimed that Philadelphia's John Radcliffe had approached him with an offer of $175 in exchange for making calls favorable to the White Stockings.

[1] According to McLean, Radcliffe named four other players as complicit in the fix: Mack, Candy Cummings, Bill Craver, and Nat Hicks.

[1] The board of directors for the Whites met to consider these charges on September 1, and they elected not to pursue the matter further with any players but Radcliffe, describing McLean's claims as "hearsay".

[1] The stockholders of the club voted to expel Radcliffe on September 8, by a count of 26–15, but he appealed to the judiciary committee of the National Association, and was reinstated on March 2, due to what Henry Chadwick characterized as procedural errors during the course of his expulsion.