Beckett, 32, has posted a 4.14 ERA (36 ER/78.1 IP) while going 4-7 in 12 starts for the Red Sox this year. He has held opponents to two runs or less in four of his last six starts, tallying a 2.68 ERA (13 ER/43.2 IP) with 30 strikeouts compared to six walks over the six-start stretch with a 2-3 record in that time. Acquired by Boston from Florida prior to the 2006 season, Beckett has gone 129-88 with a 3.85 ERA (770 ER/1,800.0 IP) and 1,677 strikeouts in 291 career Major League games (288 starts) with the Marlins (2001-05) and Red Sox (2006-12).
Mortensen, 27, will be in his second stint with Boston this year. He was previously recalled on May 2 and posted a 0.96 ERA (1 ER/9.1 IP) with 12 strikeouts and no walks in three relief appearances for the Red Sox from May 2-9. In his 15 games with the PawSox in 2012, he has gone 4-2 with two saves, a 2.39 ERA (7 ER/26.1 IP) and 24 strikeouts while holding opponents to a .165 clip (15-for-91). Acquired by Boston from Colorado in January, the right-hander has appeared in 27 Major League games (13 starts) with the Cardinals (2009), Athletics (2009-10), Rockies (2011) and Red Sox (2012), going 4-8 with a 4.74 ERA (55 ER/104.1 IP) and 62 strikeouts, including a 3.00 ERA (12 ER/36.0 IP) in 14 Big League relief appearances.