Koji Uehara could get chances in the ninth inning, but Farrell said he'd prefer to leave the right-hander in the eighth-inning setup role. Tazawa had 18 strikeouts and three walks in 14 1/3 innings this season.
Right-handed starter Allen Webster replaced Hanrahan on the 25-man roster Tuesday.
Colorado Rockies first baseman Todd Helton pleaded guilty to driving while impaired on Tuesday. He was sentenced to 24 hours community service and one year probation, in addition to a fine of $400.
Helton was arrested on February 6, when the Rockies issued a statement saying "Todd is taking full accountability for his actions with his family, his fans and the organization. The man we have grown to know has strong values that are grounded in his family and hard work. Todd clearly understands the severity of the situation."
Pittsburgh Pirates right-hander James McDonald, scheduled to start Tuesday's game against the Seattle Mariners, was placed on the disabled list after he experienced what the team described as shoulder discomfort.
Jeanmar Gomez started in place of McDonald, who is 2-2 with a 5.76 ERA in six starts this season but has struggled with control issues while walking a National League-high 20 batters.