Abad, making his first appearance on a Major League roster, went 4-3 with a 2.50 ERA in 14 games, including four starts, at Corpus Christi. He posted a 1.93 ERA as a reliever.
"He's been throwing the ball pretty well," Astros manager Brad Mills said. "His last four outings have been real good. He's a left-hander who's a strike-thrower, so we're interested to see what he's able to offer us."
With the addition of Abad, the Astros have three left-handers in the bullpen, including Tim Byrdak and Gustavo Chacin. Mills said the veteran Byrdak would be used as his lefty specialist. Abad was holding left-handers to a .277 batting average in the Minors.
"It's nice to have two lefties in the pen, so it is kind of a luxury to have three. But it's going to be interesting to see what kind of role he's going to be able to fit into, and how we're going to define how he's going to be able to be used," Mills said.