Mengden was outrighted to Triple-A Omaha on Saturday.
Mengden joined the major-league roster as a replacement player after Joel Payamps (illness) landed on the COVID-19 injured list, but he'll head back to the minors after Payamps was activated Saturday. Mengden made four relief appearances during his time in the majors, and he posted a 2.08 ERA and 1.15 WHIP with one save in 4.1 innings.