Valenzuela was notable for his unorthodox windup and for being one of a small number of pitchers who threw a screwball regularly. Never a particularly hard thrower, the Dodgers felt he needed another pitch; he was taught the screwball in 1979 by teammate Bobby Castillo.
Valenzuela was signed by the Dodgers on July 6, 1979 and debuted late in the 1980 season. In 1981, in what came to be called “Fernandomania”, Valenzuela rose from relative obscurity to achieve superstardom. He won his first eight starts (five of them shutouts). Valenzuela finished with a record of 13-7 and had a 2.48 ERA; the season was shortened by a player’s strike. He became the first, and to date, the only player to win both Cy Young and rookie of the year awards in the same season.
Valenzuela had the best period of his career from 1981 to 1986. He was named a National League (NL) All-Star in each season and won a major league-leading 21 games in 1986, although Mike Scott of the Houston Astros narrowly beat him out in the Cy Young Award voting. Valenzuela was also known as one of the better hitting pitchers of his era. He had ten career home runs and was occasionally used by Los Angeles Dodgers manager Tommy Lasorda as a pinch-hitter. For the remainder of his Dodgers career, however, Valenzuela was less effective due largely to shoulder problems. He was on the Dodgers’ 1988 World Series championship team, but he did not play in the postseason due to his ailing shoulder. On June 29, 1990, Valenzuela pitched his only major league no-hitter in a 6-0 win against the visiting St. Louis Cardinals. The no-hitter was notable for being the second one pitched that day, as right-hander Dave Stewart of the Oakland Athletics had no-hit the Toronto Blue Jays a few hours earlier. However, after the season, Valenzuela was released by the Dodgers. The remainder of his career was spent with the California Angels, the Baltimore Orioles, the Philadelphia Phillies, the San Diego Padres, and the St. Louis Cardinals.