Rumbelow (elbow) was activated off the DL at the beginning of the month and sent to Double-A Trenton.
Rumbelow had been sidelined since April of 2016 after undergoing Tommy John surgery, but the 25-year-old didn't show any rust in retiring the only three batters he faced in his season debut Friday. The righty has some experience working out of the bullpen for the big-league club, but after missing about 14 months, he'll likely stay down in the minors for the time being.