Valdez began his professional playing career on May 4, 1983, when he was signed by the San Diego Padres as an amateur free agent.

In 1987, Valdez was sent down to class "A" and spent time with the Florida State League's Charlotte Rangers before returning to the Drillers.

After being picked up by Toronto, Valdez was assigned to the triple-A Syracuse Chiefs of the International League, where he finished the 1991 season.

After signing with Milwaukee, the Brewers assigned Valdez to the Denver Zephyrs of the triple-A American Association for the 1992 season.

On May 26, 1998, Valdez was purchased by the Arizona Diamondbacks from the New York Mets and assigned to the Tucson Sidewinders of the triple-A Pacific Coast League.

Valdez had a career highlight that season when he made a return to the Major Leagues in 1998 playing with the Arizona Diamondbacks.