To take Downs' place in the bullpen, the Angels recalled left-hander Hisanori Takahashi from Triple-A Salt Lake City, where he had been optioned Saturday.
This season, Downs has matched his career high with nine saves. He also leads the team with 17 holds and 38 appearances. In six games since the All-Star break, he has allowed nine earned runs, raising his ERA to 2.57.
Manager Mike Scioscia said he did not believe Downs' reduced effectiveness resulted from the injury.
"It just came up during his last outing," Scioscia said. "His velocity was where it had been. He was just getting into more hitters' counts."
In 35 appearances for the Angels this season, Takahashi is 0-2 with a 4.37 ERA.