Valdez (0-1) allowed two runs on three hits and one walk while striking out three in Tuesday's 6-4 loss to the Rangers.
Valdez, a minor-league starter being used as a reliever in the majors, made his season debut Tuesday when the Astros needed length after starter Justin Verlander was chased in the fifth inning. The left-hander worked a scoreless sixth inning but ran into trouble in the seventh. With the pull-happy Joey Gallo at the plate and baserunners on second and third in a tie game, the Astros could not deploy their usual shift against the slugging left-handed batter, who pulled a groundball against a traditional look into right field to plate the go-ahead runs. Valdez will continue to work in a similar role and could be deployed as a spot starter if needed.