A versatile infielder and outfielder, Kopff played for St. Louis University in 1978, and later became the Billikens head baseball coach from 1984 to 1986. He batted .302 as a freshman on the Billikens team. He played second base, third base, left field, and right field. He was a left fielder for the 1979 Meramec Community College team that advanced to the JUCO World Series in Grand Junction, Colorado. In 1980 and 1981, Kopff was the starting second baseman for SIU-Edwardsville. He played in 95 games during that time, and had a composite batting average of .290. In 1983, he was a coach on the SIUE team that advanced to the College World Series. The team was inducted into the SIUE Athletics Hall of Fame. From 1978 to 1981, Kopff was a shortstop and second baseman for the Sotolar Pointers. In 1980, he was named MVP of the CYC League. That year, he set two Sotolar Pointer team records with 106 hits and a .491 batting average. His slugging percentage was .704. He had 56 RBIs, 34 walks, 26 doubles, and 7 triples. In 1982, Kopff spent six months in the Netherlands as the head coach and lead trainer of the Benco Braves, a baseball team in Gouda, Holland. His team won the Holland Baseball League championship. From 2005 to 2008, Kopff was the manager of the Crestwood American Legion baseball team.