Valenzuela's career started in 1980 as a September call up from the minor leagues for the Los Angeles Dodgers. He pitched well in his ten games out of the bullpen. In 17 innings of work, Valenzuela didn't give up any earned runs and struck out 16 innings. It was the following year where Valenzuela became a star in baseball.
Roughly 24 hours before opening day of 1981, Dodgers' scheduled starter, Jerry Reuss was injured and Valenzuela was named as the replacement. For the game, he pitched a shut out against the Houston Astros, winning 2-0. From there, Valenzuela went on to start the season with a 8-0 record with five shutouts and an ERA of 0.50.
Due to his success on the mound, unique pitching delivery( he would look up to his sky on each pitch just before he threw towards the plate), and happy go lucky attitude, Valenzuela became a media sensation. He would draw huge crowds across baseball. Fans would also go out and buy anything Valenzuela was on such as magazines, posters, tshirts and baseball cards and thus creating "Fernandomania". Valenzuela finished the strike shortened 1981 season with a record of 13-7 record and ERA of 2.48 and help lead the Dodgers to a World Series title. He would also become the first player ever to win Cy Young and Rookie of the Year awards in the same season.
Valenzuela became a workhouse in the starting rotation for the Dodgers. He pitched over 250 innings each year from 1982 to 1987 and striking out over 180 batters also, including twice of 240. He was named a NL all star six times and in the 1986 game, he tied Carl Hubbell's all star game record by striking out five consecutive batters.
In addition to being a star pitcher, Valenzuela was also a good hitter. He won the Silver Slugger twice and Dodgers manager Tom Lasorda would use him on occasion as a pitch hitter or in a long extra inning game, Valenzuela would play in the outfield or at first base. He also won the Gold Glove for excellent fielding in 1986.
By the end of the decade, Valenzuela started to get arm problems due to the accumulation of innings pitched and throwing his signature screwball. He became a less effective starter but did manage to throw a no-hitter in 1990, his last year with Dodgers. Valenzuela went on to pitch in the majors until 1997 for 5 different teams including a couple years of resurgence in San Diego.
Today, Valenzuela is a legend in Mexico and was inducted in the Hispanic Heritage Baseball Hall of Fame in 2003. Also, no Los Angeles Dodger has worn Valenzuela's #34 jersey since.