Born and raised in Covina, California, Valenzuela graduated from Bishop Amat Memorial High School.
[4][5] In 2000, Valenzuela made 16 appearances with 13 starts and one complete game, with a 5–4 record and 4.20 ERA and helped Pepperdine win a second straight WCC West Division title.
[8] He also coached 2008 WCC Pitcher of the Year and fourth overall selection in the MLB Draft Brian Matusz, in addition to other future Major Leaguers A. J. Griffin and Sammy Solis.
[8][9] On September 15, 2009, rival San Diego State hired Valenzuela to be pitching coach on the staff of Tony Gwynn.
[2] On June 9, 2019, Valenzuela was named the head coach of the Long Beach State Dirtbags baseball program.