 On June 14, 2008, Michalak signed a minor league contract with the Florida Marlins and was assigned to their Triple-A affiliate, the Albuquerque Isotopes.After his release from the Marlins organization, he signed with the Oakland Athletics and assigned to their Double-A affiliate, the Midland RockHounds, on August 2, 2008.He became a free agent at the end of the season.