Daniel Ponce de Leon entered the regular season in the St. Louis Cardinals rotation, partly because of injuries to Miles Mikolas and Kwang Hyun Kim. But manager Mike Shildt trusted him enough to start games and envisioned him sliding into the bullpen once Mikolas and Kim returned.
At first, it worked. Ponce de Leon threw five innings of one-run ball in a victory against the Miami Marlins on April 5, throwing 83 fastballs in 93 pitches, completely bypassing a curveball that had been effective for him in the past. He struggled after that, failing to hit the strike zone consistently, and went from the rotation to the bullpen to getting into an argument with star catcher and future Hall of Famer Yadier Molina.