Atlanta acquired Mederos from the Angels on Friday in exchange for international bonus pool money and optioned him to Triple-A Gwinnett.
The right-hander was waived by the Halos last weekend and is now headed to a new organization. Mederos appeared in five games (three starts) for Anaheim last year and had a 7.41 ERA and 14:12 K:BB over 17 innings, though he was more effective at Triple-A with a 3.39 ERA and 1.34 WHIP across 16 starts.