The Orioles' decision to designate reliever Stu Pomeranz for assignment and allow him to become a free agent was related to a back injury that will require surgery. The club is in the process of arranging the surgery for Pomeranz, according to an official. He won't pitch in 2013. The injury involves a vertebrae in Pomeranz's lower back and is considered pretty serious, according to another member of the organization. However, the Orioles could choose to re-sign him to a minor league deal. Manager Buck Showalter has spoken highly of Pomeranz and hoped to get him on the expanded roster in September, but the right-hander's health wouldn't allow it. Pomeranz, 27, didn't permit an earned run in 23 1/3 innings over 10 appearances divided evenly between Double-A Bowie and Triple-A Norfolk. He walked three and struck out 35. Pomeranz gave up two runs in six innings with the Orioles. He tore his left oblique on May 27, was transferred to the 60-day disabled list on June 6 and apparently sustained the back injury while rehabbing in Sarasota. The Orioles designated Pomeranz for assignment last night to make room on the 40-man roster for infielder Yamaico Navarro, who was acquired from the Pittsburgh Pirates for minor league right-hander Jhondaniel Medina. The Orioles later announced that Pomeranz was non-tendered, along with first baseman Mark Reynolds and infielder Omar Quintanilla, making all three players free agents. The St. Louis Cardinals selected Pomeranz in the second round of the 2003 First-Year Player Draft. He pitched for the independent New Jersey Jackals of the Canadian-American Association in 2009, and the Orioles signed him to a minor league deal on Feb. 3 with an invitation to spring training. Pomeranz has overcome injuries and alcoholism, which he's acknowledged, in order to get his career on track. Now he's faced with another health crisis.