Poor front office decisions that have set the club back
Every fan can rattle off the names of former players that would have been huge contributors to the Cardinals this year. Zac Gallen, Sandy Alcantara, Randy Arozarena, and Adolis Garcia are the big names that the John Mozeliak regime has let go of in recent years, but we also know the investments they've made in other players have also been damaging in the club,
Starting with those guys that were traded away, Gallen and Alcantara would have transformed this rotation into no longer a weakness, but one of the best units in baseball. A lot of the Cardinals' troubles began due to a lack of innings from their rotation, which compounded into the bullpen being strained, and then the lineup starting to look flat. Being able to rely on those two at the top with names like Jack Flaherty, Adam Wainwright, and Matthew Liberatore surrounding them would have been huge. Who knows, maybe they could even have one or two of Miles Mikolas or Jordan Montgomery in that rotation too.
Arozarena and Garcia could have taken pressure off of the Cardinals' other big bats, and truly been the best offense in baseball. It's not fair to say the Cardinals are a bad organization for missing on all of these guys - every organization misses on talent, but it's been glaring in recent years.
It's especially frustrating with the guys who are having success elsewhere are the guys who could fill your biggest needs. The Cardinals' outfield has been a mess for years, and Arozrena and Garica could have stabilized that with Jordan Walker. The Cardinals' rotation has lacked dynamic arms, and the combo of Gallen and Alcantara changes that in a big way.
Not only that, but they've almost invested poorly in free agency as well. The Steven Matz contract has been a huge mistake, Wainwright is making too much money for the production he is giving, and outside of Contreras, they just have not been aggressive in free agency to go after the players they truly need, such as a Marcus Stroman, Nathan Eovaldi, Kevin Gausman, or others who have been available.