Hernandez, now 32, spent a good chunk of his career with the Diamondbacks, spending 2011-2015 in Arizona before signing with the Phillies in free agency. He has quietly posted a strong 2.23 ERA and 1.86 FIP in 36.1 innings for the Angels since being acquired in a trade with the Braves in April.
Arizona has been looking for relief options in front of closer Fernando Rodney all summer, also being linked to options like Addison Reed and Brandon Kintzler. Hernandez will be a free agent at the end of the season, joining J.D. Martinez as rentals joining the club for the playoff push.
Madero, 20, has posted a 5.69 ERA and 1.388 WHIP in nine starts at Rookie-level Missoula and Lo-A Hillsboro so far this season. He wasn’t ranked among the top 30 prospects in Arizona’s system at the time of the deal.