Miami Marlins
Like the White Sox, the Miami Marlins have been on a one-way ticket toward a fire sale since the first month of the season. They already traded their best hitter Luis Arraez to the San Diego Padres earlier this season, and they will surely be looking to capitalize on other assets as the deadline nears.
Unlike the White Sox though, a lot of the Marlins' best assets are dealing with injury issues at the moment, making their firesale a lot more complicated than you would think. Top starters like Sandy Alcantara, Jesus Luzardo, Braxton Garrett, Edward Cabrera, and Ryan Weathers are all on the injured list right now, so they may not actually be the best partners for the Cardinals to grab a starting pitcher.
Unless one of those arms like Weathers or Garrett gets healthy quickly, the Cardinals would likely have more interest in the bullpen arms the Marlins have on hand instead.
The big fish they have to offer right now is left-hander Tanner Scott, who is set to hit free agency after the season and is one of the best relievers in baseball. He's posted a 1.54 ERA in 35 innings this year and is more than comfortable closing games if needed. Like JoJo Romero, Scott can shut down both right-handed and left-handed hitters, so if the Cardinals added him to the back of their bullpen, it would be a truly elite group of players they can turn to late in games.
One of the ways the Cardinals can give themselves an edge in October would be by doubling down on how good their bullpen has been. While their starters may not stack up with the other playoff teams they'll face, they could go to their bullpen early and often to shut down other lineups.
Scott might be a bit too expensive though, so maybe a name like JT Chargois could be a target for them. He's a right-handed reliever who hasn't thrown much this year but has been highly effective so far and has been in the past as well.
The Marlins have to be kept tabs on with how bad they are, but unless they can get healthier, the options the Cardinals would be interested in are thinner than other clubs.