The Angels optioned Rosenberg to Triple-A Salt Lake on Wednesday.
Rosenberg's demotion doesn't come as a major surprise after he was pressed into long-relief duty behind Noah Syndergaard in Tuesday's 9-1 loss to the Yankees. After Syndergaard exited midway through the third inning, Rosenberg proceeded to work five innings, giving up four earned runs on five hits and two walks along the way. The Angels called up Andrew Wantz from Triple-A to join the bullpen as a replacement for Rosenberg, who wasn't going to be available for a few days following the 99-pitch outing.