Rosenberg has been building back up after his arm "didn't feel great" following a period on paternity leave, Sam Blum of The Athletic reports.
Rosenberg last pitched for Triple-A Salt Lake on July 3 and went on paternity leave soon thereafter. The southpaw discovered that his arm didn't feel right upon his return, but he's now throwing and hopes to be able to return to game action in a few weeks. Rosenberg has pitched in three major-league games with the Angels this season, posting a 4.22 ERA, 1.41 WHIP and 8:6 K:BB over 10.2 innings.