 He was signed by the New York Yankees as an amateur free agent before the start of the 1965 season.In 1965, Closter's first year in the minor leagues, he split his time between two teams, the Rookie league Johnson City Yankees of the Appalachian League and the single-A Greensboro Yankees of the Carolina League.In the winter, Closter also spent time with the Yankees affiliate of the Florida Instructional League.