"They were just unlucky!" - True
Baseball is a game of centimeters...and luck. The environment at the ballpark can change a sure-fire home run to a deep pop fly. Hitters have no effect on the ball once it is put in play. Their job is done once the bat hits the ball.
However, there are some stats that can point to luck. wOBA (weighted on-base percentage) and xwOBA (expected weighted on-base percentage) when compared can show how unlucky a team truly was. If a team's wOBA is less than their xwOBA, the team experienced a reasonable amount of bad luck.
In 2023, the Cardinals have a wOBA of .323 and an xwOBA of .334. Their difference of -.011 indicates a bit of bad luck. For context, the Cardinals have the fourth-greatest negative gap between their wOBA and their xwOBA. Only the Yankees, Royals, and Tigers have experienced more bad luck according to wOBA. Therefore, the Cardinals have been a bit unlucky.