November 20th at 5:00 EST was the deadline to protect prospects from the major league portion of the Rule 5 draft. Before that deadline on that date, the Cardinals made the following transactions:
In January of 2018, the Cardinals signed OF Randal Grichuk to a 1-year, $2.6 million deal, avoiding arbitration. The Toronto Blue Jays also avoided arbitration with RHP Dominic Leone by signing him to a 1-year, $1.085 million contract. Leone had just barely qualified for arbitration as a Super Two player. One week after the Cards signed Grichuk, the Cards traded him to the Blue Jays for Leone and RHP Conner Greene.