Saarloos quickly rose in the Astros organization, making brief stops with the Double-A
Round Rock Express and the
Triple-A New Orleans Zephyrs 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 ERAin 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. 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 the Triple-A
Sacramento River Cats, where he pitched well enough to receive a call-up and start five games for Oakland. In , with
Mark Mulder and
Tim Hudson traded away, the Athletics had openings in their rotation. Saarloos beat out
Keiichi Yabu and
Juan Cruz to win the last starter spot in the rotation. Saarloos succeeded, going 10–9 with a 4.17 ERA in 27 starts. He was widely considered to be among the best #5 starters in the
American League, sporting one of the lowest home run rates. With the signing of veteran starter
Esteban Loaiza before the season, the Athletics bumped Saarloos to the bullpen. Soon after,
Rich Harden got injured, and Saarloos was put in as a fifth starter for a few games. He was also used in many varying relief roles, much like
Justin Duchscherer was in 2005, but also as a spot starter. Shifting between the bullpen and the rotation, Saarloos finished with a record of 7–7 in 35 games for the A's. He allowed more home runs (19) than the previous season (11). On January 19, , Saarloos signed a one-year $1.2 million deal with the Athletics. On January 23, 2007, Saarloos was traded to the
Cincinnati Reds for minor league reliever David Shafer. Both teams also received a player to be named later. On May 28, 2007, Saarloos was sent to the minors after failing to retire any of the seven batters he faced in a 14–10 loss to the
Pittsburgh Pirates the night before. In his lone season with the Reds, Saarloos had a 7.17 ERA in 42.2 innings. On October 12, 2007, Saarloos was outrighted to the minor leagues. He refused the assignment and became a
free agent. On January 15, , Saarloos signed a minor league contract with an invitation to
spring training with the Oakland Athletics. On April 14, he was added to the major league roster but was designated for assignment on April 23. He was sent outright to Triple-A on April 25. On August 18, Saarloos was recalled. He became a free agent at the end of the season. Saarloos signed a minor league contract with an invitation to spring training with the
Cleveland Indians in January ; after training camp, he was sent to minor league camp on March 24, 2009. He went 3–10 in 16 games at the AAA level. He retired after the 2009 season. ==Scouting==