Gsellman (ribs) was transferred to the 45-day injured list after Game 1 of Saturday's doubleheader against the Nationals, Tim Healey of Newsday reports.
The 27-year-old landed on the shelf with a fractured rib in early September and wasn't expected to return this year, so it's just a procedural move to create some space on the 40-man roster. Gsellman finished 2020 with a 9.64 ERA, 2.14 WHIP and 9:8 K:BB over 14 innings across six outings (four starts).