Jordan Walker
One of the more frustrating developments of the 2023 season had to do with prized rookie Jordan Walker. He got off to a hot start, hitting safely in each of his first 12 games. Out of all the Cardinals outfielders, he was performing the best, hitting .274 with two homers.
But in a stunning move, the Cardinals sent him down to Triple-A Memphis because they wanted to see him hit the ball in the air more than on the ground. That resulted in him struggling in Memphis until he picked things up at the end of May.
Walker was called back up on June 1 and ended up finishing the season strong, while also improving defensively in right field, but the Cardinals made a mistake by sending him to the minors, and things might have improved offensively if they hadn't sent him down in the first place.