The Athletics recalled Alvarado from Triple-A Las Vegas on Friday.
The team DFA'd Joel Kuhnel in a corresponding move. Alvarado pitched in 10 games out of the Athletics' bullpen earlier this season and posted an 8.38 ERA, 1.86 WHIP and 9:7 K:BB across 9.2 innings. He has a 2.25 ERA and 16:4 K:BB across 12 innings with Las Vegas.