Stand pat
I've seen this thrown out a lot on social media, and honestly, it feels like an overreaction. Remember when the Cardinals signed Lynn and Gibson and people thought they weren't going to make a significant move? A week later they signed Sonny Gray.
It's not even the middle of December yet and most teams in baseball still have a ton of work to do on their rosters. Sure, the Cardinals could be done with their moves, but they still have plenty of time to further improve the roster.
Let's explore this scenario though, because even though I find it extremely unlikely, it's possible. The Cardinals have added three starting pitchers (Gray, Gibson, and Lynn), two relievers who will likely factor into their bullpen (Ryan Fernandez and Nick Robertson), and helped clear some of their outfield log-jam by trading O'Neill. In theory, they've done everything they hoped to do entering this offseason, so everything else they could do is more of a "want" in their eyes.
Even if they are thinking like that, I still believe that's more likely to lead them toward more aggressive moves, but sure, it could lead them to stand pat as well. They would enter the season with over $20 million in salary flexibility to add significant pieces at the trade deadline based on the needs that arise during the season. They can let their pitching show its true colors in the first half and then decide to add the right pieces to that mix in July. They can see how their outfield pieces play and still have significant bats and prospects they could move for a bigger piece.
It really wouldn't be a shock to see the Cardinals be done with their moves for now and come back to the table later, but if they did so, it would be very disappointing. They've done enough to make themselves a fringe playoff team and still have so much money and assets to improve further, it would feel like a huge missed opportunity if they decide to stay as they are.