The Cardinals selected Rajcic's contract from Triple-A Memphis on Thursday.
A sixth-round pick in the 2022 First-Year Player Draft, Rajcic's career had stalled out as a starting pitcher. However, he has blossomed this season after moving to the bullpen, posting a 2.88 ERA and 46:14 K:BB over 40.2 innings with Memphis. Rajcic will be making his major-league debut when/if he enters a game, and he'll likely fill a multi-inning middle relief role.