Escobar, who had spent the whole season on the DL with left elbow inflammation, was activated following the completion of a two-game rehab assignment. He pitched one inning with Class A Greenville on Tuesday and worked two more frames for Pawtucket on Friday.
Escobar made his Major League debut with the Sox last season, allowing one run over two innings, after being acquired from the San Francisco Giants on July 26. The 23-year-old is the organization's 18th-ranked prospect, according to MLB.com.
Alec Shirkey is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.