Atchison, 36, leads Red Sox relief qualifiers with a 1.76 ERA (9 ER) and ranks second in the American League with 46.0 innings out of the bullpen. The right-hander has fanned 34 batters with just nine walks over 37 outings. In 150 career Major League appearances (1 start) over parts of six Major League seasons with the Mariners (2004-05), Giants (2007) and Red Sox (2010-12), Atchison is 7-7 with one save, a 3.57 ERA (81 ER/204.1 IP) and 162 strikeouts compared to 59 walks. His 2.36 ERA (20 ER/76.1 IP) since the start of 2011 is the ninth-lowest mark among American League hurlers with at least 75.0 innings in that stretch.
The 26-year-old Tazawa begins his second stint with Boston this season. He did not allow a run in five relief appearances with the Red Sox, with four strikeouts, no walks and five hits allowed over 6.1 innings from April 18-30. He leads Triple-A relief qualifiers with an average of 11.91 strikeouts per 9.0 innings (56 K/42.1 IP) in 25 relief appearances for the PawSox this season, going 3-2 with four saves and a 2.55 ERA (12 ER), and has not allowed an earned run in his last six outings (9.2 IP). Of his 25 outings in Triple-A, 14 have been 2.0 innings or longer. Signed by Boston as an international free agent on December 3, 2008, Tazawa is 2-3 with one save and a 5.97 ERA (23 ER/34.2 IP) in 14 career Major League games for the Red Sox, including four starts in 2009.