Arredondo, 25, led all Major League relievers in victories last season, when he was 10-2 with a 1.62 ERA in 52 appearances as a rookie. He suffered the loss Sunday at Detroit and is 1-3 with a 5.55 ERA in 25 appearances this season.
"Jose needs to work some things out," said Angels manager Mike Scioscia. "We saw what his upside was last year, how important he was, and how we were relying on his continued progression this year. He's obviously taken a small step backwards right here in the first two months. It doesn't seem like he's moving in the right direction with his stuff and his command. He needs to work it out."
Jepsen, 24, was 0-1 with a 4.32 ERA in nine appearances with the Angels last season. In 14 appearances this season with Salt Lake, he's 1-0 with a 9.00 ERA and two saves.
"His role's going to be when he gets the ball, go in there and get guys out," Scioscia said. "I'll probably slot him somewhere in the middle until he gets his feet on the ground. His numbers weren't great in Triple-A, but the reports were encouraging. He's taken some big steps forward as far as some of the things he was working on."
The Angels' bullpen came into Tuesday's game with an ERA of 5.78, worst in the American League.
Carter Gaddis is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.