Previously, Wakamatsu spent four years as the Rangers' bench coach and one year as their third base coach. Prior to his tenure with the Rangers, Wakamatsu coached in the Los Angeles Angels of Anaheim, Arizona Diamondbacks, Cleveland Indians, Seattle Mariners, and Chicago Cubs organizations. He was the Manager of the Year in the California League in .
As a player, Wakamatsu made it to the Majors only briefly, as a backup catcher for the Chicago White Sox in .