O'Reilly was an outstanding outfielder for 20 years in local amateur baseball. He played shortstop, second base and third base with some of the better clubs in the seeded leagues. His teams included Moloney Electric, Pelligren Construction, Carondelet Sunday Morning Club, Giesler-Jorgen, Wright Ford, etc. He played for titlists in the strong U. City League, the Muny League, and the St. Louis County League.