1. Sonny Gray
Out of everyone on this current roster, Sonny Gray is the most irreplaceable. This is because of the pitching conundrum the Cardinals found themselves in last year. They had no depth and the quality of starting pitching was also lacking.
Gray is the undisputed ace of this year's staff. For the first time in a few years, the Cardinals actually have somebody that can be considered as such.
Beyond Gray though, the rest of the rotation is human. Miles Mikolas didn't have his best year, Steven Matz couldn't stay healthy, and Kyle Gibson and Lance Lynn are gambles. If Gray gets hurt and the best the Cardinals have is Mikolas, they're going to be in a lot of trouble and could even sink back to where they were at the end of the 2023 season, in last place in the NL Central.
It will prove once again that the Cardinals have not properly addressed their pitching staff. Most good teams have at least two frontline starters. Beyond Gray, none of the other starters can be considered frontline guys.
But if Gray is healthy and repeats his performance from last year, the Cardinals should be just fine. But they really need Gray to be healthy. They banked a lot on signing three starters above the age of 33 and going into the season with Matz, who is set to turn 33, as the youngest of the group.
Hopefully Gray gives the Cardinals exactly what they need in 2024.