The former Pirates eighth-round Draft pick in 2006, Presley has played in parts of the past four seasons with the Twins and Bucs. He has a .264 career batting average to go along with 17 home runs, 32 doubles, 15 triples, 60 RBIs and 20 stolen bases in 232 games.
"[Presley is] a versatile left-handed-hitting outfielder with speed and a good approach at the plate," Luhnow said, "and [he] has had tremendous success in the Minor Leagues, and has had success against us.
"We were excited when he became available. He's the type of player you hope becomes available through a waiver claim. He was competing for the everyday center-field job in Minnesota and didn't get it, so I guess they decided they didn't have a spot on the roster for him. We're going to accommodate him."
Presley is a career .292 hitter with a .352 on-base percentage in the Minor Leagues and can play all three outfield positions. He figures to be a valuable asset with his ability to pinch-hit, pinch-run and make the occasional start.
The Astros wanted to carry eight relievers to avoid a scenario they had last year, when the bullpen was decimated in mid-April after starting pitchers failed to escape the first inning three times in a five-game span. Also, Houston begins the year with 13 consecutive games without an off-day, which could put an extra workload on the pitchers.
"Unless something comes up, we're going to start the season with 12 pitchers," Luhnow said. "We are hopeful to maintain Raul in our system, and down the road I'm sure they'll be a chance for him to pitch in the big leagues for us or someone else. Right now, we felt the opportunity to get a player of Presley's caliber was worth it to go back down to 12 pitchers."
The Astros have yet to set the 25-man roster, and Luhnow said they continue to monitor the waiver wire.
Brian McTaggart is a reporter for MLB.com and writes an MLBlog, Tag's Lines. Follow @brianmctaggart on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.