Balfour, 37, had not allowed a run in 3 2/3 innings entering Saturday's game against the New York Yankees, but walked three batters and allowed a grand slam in 2/3 of an inning in the Rays' 9–0 loss at Tropicana Field.
Balfour signed a two-year, $12 million deal with the Rays prior to last season and was due $7 million this season. He appeared in 65 games in 2014, going 2–6 with a 4.91 ERA, 57 strikeouts and 41 walks.
Balfour was an All-Star in 2013 with the Oakland Athletics, posting a 2.59 ERA with 72 strikeouts and 27 walks over 62 2/3 innings.
Saturday's loss dropped the Rays to 6–6, a game and a half behind the Boston Red Sox in the American League East.
- Mike Fiammetta