Houston Astro pitcher Brandon Backe was put on the 15-day disabled list Friday because of a sprained ligament in his right elbow.
Backe left in the second inning of the Astros' 5-3 loss to San Francisco on Thursday. He flew to Houston and had the elbow examined Friday.
Right-hander Ezequiel Astacio, who started 14 games last season, was recalled from triple-A Round Rock. Astacio was 3-6 with a 5.67 earned-run average last season.
Backe skipped his first scheduled start of the season on April 5 -- his 28th birthday -- because of a sore back. He returned two days later and earned a win against the Washington Nationals, giving up a run and three hits in six innings.
Houston's rotation lacks experience: Wandy Rodriguez, 27, is starting his second major league season, and Taylor Buchholz, 24, and Fernando Nieve, 23, are rookies.
The Boston Red Sox sent first baseman Hee-Seop Choi to triple-A Pawtucket for a rehabilitation assignment that began Friday.
Choi, claimed off waivers from the Dodgers on March 24, was put on the 15-day disabled list April 1, retroactive to March 29, because of a strained left hamstring.
He is Boston's third-string first baseman behind Kevin Youkilis and J.T. Snow.
Right-handed relief pitcher Jay Witasick was put on the 15-day disabled list by the Oakland Athletics because of a sprained left ankle. Outfielder Bobby Kielty was recalled from Sacramento of the Pacific Coast League to take his place on the roster.... The New York Yankees recalled left-handed reliever Matt Smith from triple-A Columbus on Friday and designated catcher Koyie Hill for assignment.... Left-hander C.J. Wilson was activated from the disabled list by the Texas Rangers, who optioned right-hander Scott Feldman to triple-A Oklahoma.