Astros general manager Jeff Luhnow said Blackley will be used in long relief.
"He's a left-handed long man, which is something we've been trying to figure out how to work into our roster," Luhnow said. "He had a lot of success as a starter and we believe that will translate well into our bullpen. We did have our scouts see him this spring and there was a long list of players that became available as the season started when everybody cut down to 25 [players]. He was at the top of our list, and we made a few phone calls and got it done."
Blackley played a key role in the A's run to the AL West title in 2012, going 6-4 with a 3.86 ERA. He struck out 69 batters and walked 30 in 102 2/3 innings. The southpaw has pitched over 1,100 innings in the Minors.
The Astros will have to clear a spot on the 40-man roster on Friday, but Luhnow said adding Blackley gives them more flexibility.
"There's some good lineups we're going to be facing with left-handed hitters, and four of our five rotation guys are right-handed, so if you follow them up with a left-handed long man, it gives you a platoon advantage that's nice to have," Luhnow said. "He's been effective against lefties and righties."
Blackley has held right-handers to a .269 batting average and left-handers to a .243 batting average in his career, which has included stops in Seattle and San Francisco. He's one of three Astros players who played for the A's organization last year, joining starting pitcher Brad Peacock and outfielder Chris Carter.
Peacock and Carter came to Houston two months ago in the trade that sent Jed Lowrie and Fernando Rodriguez to Oakland.
Goebbert, a 13th-round Draft pick from Northwestern in 2009, spent the majority of the '12 season in Double-A Corpus Christi, where he hit .304 with a .399 on-base percentage. The 25-year-old has drawn 176 walks to go with 262 strikeouts in more than 1,500 Minor League at-bats.
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.