Ross, 25, was sent to Pawtucket after posting a 6.17 ERA and a 1.71 WHIP across 13 appearances earlier this season but returns to the Red Sox bullpen in a long relief role as Justin Masterson lands on the 15-day disabled list.
Masterson will get some rest after being diagnosed with what the team termed right shoulder tendinitis. He will then conceivably work with one of the Red Sox minor league affiliates before making a return to the big leagues. He had an eye popping 6.37 ERA and 1.67 WHIP in 35 1/3 innings (seven starts) this season.
Masterson has struggled to match his All-Star season of 2013 which saw him win a career high 14 games while posting a 3.45 ERA with the Cleveland Indians.