Saarloos quickly rose in the Astros organization, making brief stops at Double-A Round Rock and Triple-A New Orleans before being called up to the major leagues in his second year as a professional. In , he went 6-7 with a 6.01 ERA with Houston and was sent down to New Orleans for the next season. In , he again pitched very well in the minors but posted a 4.93 ERA in 36 games for the big club. He also contributed to the Astros' six-pitcher no-hitter of the New York Yankees on June 11, throwing the last out of the third inning and all of the fourth. It was around this time he caught the eye of Oakland Athletics assistant general manager Paul DePodesta. A few weeks into the season, after appearing in only two games for New Orleans, he was traded to the Athletics for Chad Harville. They sent him to Triple-A Sacramento, where he pitched well enough to receive a call-up and start five games for Oakland.