Cronin began his professional career pitching in two games for the Hartford Bluebirds of the Connecticut State League in July 1895.

Joe Kelley, star player for the Orioles and son-in-law of part-owner John Mahon, reported that the team owed as much as $12,000 ($422,585 in current dollar terms).

[2] Unable to afford that debt, Mahon purchased shares of the team from Kelley and player-manager John McGraw.

That day, Freedman released Cronin, Kelley, Dan McGann, Cy Seymour, Roger Bresnahan, and Joe McGinnity from their contracts with Orioles.

[4][5] After the 1903 season, on December 12, 1903, the Giants traded Cronin with Charlie Babb and $6,000 ($203,467 in current dollar terms) to the Brooklyn Superbas for Bill Dahlen.