Etheridge played college baseball at Mississippi State University for two seasons before signing with the San Francisco Giants as an amateur free agent in 1964. After three seasons in the Giants' farm system, he made his major league debut on July 16, 1967 in the first game of a doubleheader against the Chicago Cubs at Candlestick Park. Etheridge entered the game as a late inning defensive replacement.[1] The next day, he made his first major league start; with the Giants down 4-1 in the ninth inning, Etheridge hit a two out triple to drive in Bob Schroder and Jim Davenport. With Etheridge representing the tying run at third base, the following batter, Willie McCovey, grounded out to end the game.[2]
For the season, Etheridge batted .226 with one home run and fifteen runs batted in (RBI) for the second place Giants. Though he struggled for playing time behind slugger Jim Ray Hart at third base, Etheridge was named a rookie All-Star by Topps.