The Cardinals will have plenty of young pitchers vying for innings during the 2021 season. Additionally, it appears that Carlos Martinez will re-enter the rotation, which makes him a possibl breakout candidate considering his struggles in 2020 and question marks that surround his arm. Finally, with Kwang-Hyun Kim and Miles Mikolas dealing with some soreness, the Cardinals may need pitchers like John Gant, Daniel Ponce de Leon, and Jake Woodford to step up.
To begin with, Carlos Martinez seems like the biggest breakout candidate. Even though Martinez used to be the ace of the Cardinals, he has dealt with arm issues and struggles in 2020.