Tazawa, 30, has made 35 relief appearances for the Red Sox this season, going 1-1 with a 3.62 ERA (13 ER/32.1 IP) and 37 strikeouts against only eight walks. Opponents have batted .215 (26-for-121) against the Japanese native this season, with lefties hitting only .151 (8-for-53). Signed by Boston as an international free agent in December 2008, Tazawa is 15-19 with four saves and a 3.48 ERA (114 ER/294.2 IP) in 284 career major league outings, including four starts, all with the Red Sox (2009, 2011-16). Since 2013, he ranks tied for ninth among American League relievers with 229 strikeouts.
Cuevas, 25, has made three relief appearances for the Red Sox over a pair of major league stints this season, going 0-1 with a 3.60 ERA (2 ER/5.0 IP). The Venezuelan native has also pitched in 15 games (all starts) with Pawtucket, going 6-3 with a 3.38 ERA (34 ER/90.2 IP), 57 strikeouts, and a .238 opponent batting average. A non-roster invitee to Red Sox spring training this year, Cuevas was originally signed by Boston as an international free agent in 2008. In 152 minor league appearances (91 starts)-all in the Red Sox organization-he is 44-33 with six saves and a 3.51 ERA (268 ER/688.0 IP).