Ross Detwiler was the first major league free agent signed by the Marlins once Kim Ng took over as general manager. He was a versatile reliever who was used occasionally in high-leverage situations. At least throughout the first half of the 2021 season, he put up average numbers and helped the bullpen (1-0, 4.19 ERA, 34.1 IP, 29 H, 1.194 WHIP, 41 SO).
As a pending free agent and with the Marlins out of playoff race, Detwiler was expected to be moved before the MLB trade deadline.