Nicknamed "Papelero" in his native Mexico, he threw and batted right-handed, stood 5 feet 10 inches (1.78 m) tall and weighed 175 pounds (79 kg).

He began his pro career with the Bisbee-Douglas Copper Kings, an unaffiliated team in the Class C Arizona–Texas League, then was drafted into the Cardinal organization in 1955.

After hitting .314 and .286 in consecutive seasons with the Double-A Houston Buffaloes in 1956–57, he received early- and late-season auditions with the 1958 Redbirds, spending the bulk of that year with Triple-A Omaha.

At the close of the 1958 season, Valenzuela was traded to the San Francisco Giants in a five-player transaction that netted the Cardinals right-handed pitcher Ernie Broglio.

[3] After his playing retirement, he became manager of the Alijadores de Tampico in the Mexican League, winning one title in 1975.