They aren't active enough
Since the trades of Randy Arozarena, Zac Gallen, and Sandy Alcantara, the Cardinals have been meek, too afraid to make deals for fear of getting poached again. The last thing the team can afford to do is remain petrified and be passive at the trade deadline. The Cardinals have a lot of depth in the infield and at designated hitter, the latter of which could be a free-for-all between Willson Contreras, Nolan Gorman, Alec Burleson, Juan Yepez, and Luken Baker. The Cardinals can't shy away from dealing from positions of strength, because if they do, they will be right back to this problem next year.
The Cardinals' hesitance to trade players in hopes of coaxing more out of them has led many players' value to drop. Tyler O'Neill is a prime example of this. Were the Cardinals to trade him after 2021, they could have received a massive haul for the MVP candidate. Now his value is down the drain as an often-injured outfielder who hasn't produced in two seasons.
Jack Flaherty is another player whom the Cardinals need to trade at the deadline. His value is likely at its highest since 2019, and the Cardinals risk having another O'Neill situation if they decide to hold on to Flaherty. Although the team has performed better as of late, the front office can't fall victim to the idea that there is still a chance of contention. Mozeliak said the team would get pitching, so the Cardinals need to shell out the resources to acquire some effective arms.