He was a hard-hitting catcher who signed a professional contract with the St. Louis Cardinals in 1965. In 1966, he played in the minor leagues for the Cedar Rapids Cardinals and the Gulf Coast League Cardinals. George Kissell was his manager on the Gulf Coast League Cardinals in Sarasota, Florida. Gegg played for St. Louis University from 1962 to 1965. As his team’s starting catcher, he helped the Billikens win three consecutive Missouri Valley Conference championships in 1963, 1964, and 1965. His team reached the semifinals of the College World Series in 1965. He was selected to the all-conference team as a catcher every year from 1963 to 1965. He received honorable mention as an All- American in 1965. Gegg was the head coach of the St. Louis University baseball team from 1970 to 1973. He was the player-manager of the St. Louis University Club team from 1971 to 1974. Through his efforts, this team competed in the St. Louis County League in the early 1970s. In 1975, Gegg was the player-manager of the American National Insurance team that won the St. Louis County League championship. He was a player-coach for American National in 1976, helping his team finish second in the St. Louis County League. Gegg was a catcher for St. Louis University High School from 1958 to 1961. In 1962, he was a catcher on the Kutis team that won the Ban Johnson League championship. Gegg played in the St. Louis Semi-Pro League for Kimacks in 1963 and the Red Villas in 1965. Both teams won the St. Louis Semi-Pro championship. In 1964, he was a catcher for the Springfield Capitals in the Central Illinois Collegiate League. Gegg served in the United States Army from 1967 to 1969, including a tour of duty in Vietnam. In 1988 and 1989, he was the hitting coach at Gonzaga College High School in Washington D.C. In 1996, Gegg was inducted into the St. Louis University Billiken Hall of Fame.