Left-hander Robbie Ross was optioned to Pawtucket in a corresponding move.
Ramirez struck out one batter and did not allow a hit in 1 2/3 scoreless innings of relief against the Detroit Tigers on April 8. The 27-year-old has posted an 0-1 mark with two saves and a 2.53 ERA in nine relief appearances this season with Pawtucket.
Ross has yielded seven runs on 12 hits in nine innings over eight appearances this season with the Red Sox. The 27-year-old owns a 16-12 career mark with six saves and a 3.92 ERA in 266 games (12 starts) with the Texas Rangers and Red Sox.
Ross has allowed one run on one hit in six appearances with Pawtucket this season.