ARLINGTON -- The Rangers acquired left-hander Travis Blackley from the Astros in exchange for cash considerations on Wednesday. He will be sent to Triple-A Round Rock and not be placed on the club's 40-man roster.

Blackley went 1-1 with a 4.89 ERA in 42 relief appearances for the Astros this season. He was designated for assignment by Houston on Friday and outrighted to Triple-A Oklahoma City on Saturday. The Austrailia native is 8-8 with a 5.28 ERA over 78 games (23 starts) in his four-year big league career.

The move occurred a day after Rangers general manager Jon Daniels announced Matt Harrison would be out for the season with a lingering back issue. The club recently also lost Colby Lewis for the season due to bone spurs in his right hip.

"We'll look; I think if there is something, it'll be more than likely in the protection category," Daniels said Tuesday. "We may look for some depth. I don't really have any expectations that we'll add a starting pitcher that will crack our starting five. You can always improve your depth, and that's what we're looking at."