The Cincinnati Reds have not announced their full postseason roster yet, but made it clear that Mariekson ‘Didi’ Gregorius will not be on the 25-man postseason roster. Gregorius was called up in the beginning of September as a September call-up.
Gregorius was sent to the Cincinnati Reds Spring Training and Player Development Home to stay ready in case he must substitute a player in an injury situation.
The Reds didn’t have another choice with Gregorius, he was called up to the MLB on the 1st of September and was not on the 25-man roster by August 31st.
Under Major League Rule 40 (a), the pool of players eligible for the postseason consists of the 25 players on the active roster and any players on the disabled, bereavement, suspended or military lists before midnight ET on August 31.
The only choice left by the Reds is, if an eligible player is injured and unable to play the Reds can call up any player in the organization regardless of their roster status. The replacement player need to be in the organization as of the August 31st deadline and had to finished the season in the organization, and also receive approval from the commissioner.