The A's also received cash considerations and will send the Red Sox a player to be named or cash.
Mujica, who turns 31 on Sunday, was designated for assignment by the Red Sox on Friday. In 13 2/3 innings over 11 games, he posted a 1–1 record and 4.61 ERA with eight strikeouts and three walks.
Last season, his first with the Red Sox, Mujica appeared in 64 games and posted a 2–4 record with a 3.90 ERA and eight saves.
Mujica signed a two-year, $9.5 million contract with the Red Sox in December 2013. The season prior, he was an All-Star for the St. Louis Cardinals after going 2–1 with a 2.78 ERA and 37 saves in 64 2/3 innings.
The Red Sox fell to 13–17 on Saturday after losing 7–1 to the Toronto Blue Jays.
- Mike FIammetta