Poppen was optioned to Triple-A Reno on Sunday.
The right-hander has a 2.91 ERA, 1.29 WHIP and 17:9 K:BB across 21.2 innings this season, but he'll lose his spot on the big-league roster to Dallas Keuchel, who is starting Sunday against Detroit. Poppen should receive another opportunity in the majors this year given his solid numbers.
