What to expect from Cardinals' internal pitching options in 2024

A desire to add three starting pitchers this offseason should be paramount for John Mozeliak. These additions can be achieved through trades or free-agent signings. There are plenty of options in both of these departments. The Cardinals could sign players like Sonny Gray and Martin Perez, then trade for a pitcher from Seattle or Miami. They could open up the checkbook for someone like Aaron Nola or Blake Snell then sign a low-end free agent while trading for another pitcher such as Tyler Glasnow. Perhaps, the Cardinals could even swing two trades while maintaining their depth and sign a player like Yoshinobu Yamamoto.

Gaining three new starters is a tall task. It will require a lot of resources in both the personnel and financial departments. Mozeliak will have to get creative to fill out a rotation in 2024. Should management fall short of their goal, the Cardinals may have to settle for less than three pitchers from outside and instead hope their internal improvements can rise to the challenge of being the fifth pitcher in the rotation.

That was partially the plan for 2023: hope Adam Wainwright, Miles Mikolas, Steven Matz, Jack Flaherty, and Jordan Montgomery can play to their full potential and then rely on pitchers such as Matthew Liberatore and Zack Thompson to fill in when someone got hurt. Underperformance and injuries hampered an already below-average bullpen, and the backup options didn't perform as well as expected.

Zack Thompson had adjusted to being a reliever, and his secondary pitches weren't in tune; Matthew Liberatore didn't quite reach the velocity that is necessary to get batters to whiff, and his mechanics weren't as consistent as he would have wanted. If the front office can't acquire three starters this year, the team will have to rely on internal options to step up and fill in innings.

Let's take a look at four internal options that could pitch in the starting rotation and see how they might perform in 2024.

LHP Zack Thompson

Towards the end of the 2023 season, Zack Thompson returned to the majors in a starting capacity. Up until the 2022 season, Thompson was always a starting pitcher, but he saw significantly greater success out of the bullpen, especially in the major leagues. As a starter in Memphis in 2022, Thompson had a 4.67 ERA, 1.15 WHIP, and he struck out 56 batters in just over 44 innings. As a reliever in the same year, he had a 5.00 ERA, 1.56 WHIP, and struck out 11 batters in 9 innings. Batters had a .222 batting average against him.

Thompson began phasing out of his role as a starter that year, but he did have stronger numbers as a starting pitcher. His pitch mix featured a 4-seam fastball that would touch 96 MPH and floated closer to 94-95 MPH. His curveball was his second-most used pitch, and the cutter was a pitch he was starting to develop in 2022. The cutter had a stellar whiff rate at 43.8% and an expected batting average of .199.

However, things changed in 2023 for Thompson. He began the full-time shift to the bullpen, and his statistics began to tumble, especially in the minors. As a starter in 2023 in Memphis, Thompson had a 9.73 ERA, 2.51 WHIP, and struck out only 32 batters in 28 innings; batters hit .322 against him. As a reliever for the Redbirds, Thompson had a 3.18 ERA, 1.59 WHIP, and struck out 9 batters in 5.2 innings. Thompson was much better as a reliever in 2023 in the minors.

All of this brings us to the fact that Thompson was settling into the bullpen in 2023. He has jostled around in 2022, and the stats show that. Thompson's cutter usage increased mightily in 2023, and the effectiveness of that pitch was maintained. His numbers as a starter and a reliever in 2023 are comparable, and he settled down mightily in St. Louis (4.37 ERA as a starter vs. 4.29 as a reliever, 1.32 WHIP as a starter vs. 1.62 WHIP as a reliever. His strikeout rates in general dropped this past year).

Should Thompson maintain his stamina and continue to improve his third pitch, he could very easily slot into the 5th spot in the rotation in 2023. Thompson is my personal choice for the 5th rotation spot should the front office only acquire two starters this year.

LHP Matthew Liberatore

The St. Louis Cardinals acquired Matthew Liberatore back in January 2020 for Randy Arozarena from the Tampa Bay Rays. That trade hasn't gone in the Cardinals' favor as of yet, and fans are already labeling it as one of the worst trades in franchise history. The former first-round pick had a lot of pressure on him to slide into the starting rotation in the near future.

Libby has experienced mixed results in his professional career. In the majors, Liberatore has a 5.51 ERA, 1.567 WHIP, and a strikeout rate south of 19% with a walk rate north of 16%. Those numbers are not serviceable in the major leagues, and they do not align with what he did in the minors. He is still 23 years old, so he has plenty of time to develop and become more accustomed to professional hitters.

In the minors, Liberatore has a 3.99 ERA, 1.315 WHIP, and struck out 9.4 batters per nine innings while limiting walks slightly more than he has in the majors. His curveball is perhaps his best pitch, and his fastball has always always been in the mid-90s. He has a consistent delivery, and he was once capable of leading a starting staff. However, his stuff has simply not transferred to the majors as it should have.

Handing the 5th spot in the rotation to Liberaotre probably raises the ceiling of the starting staff, but it surely lowers the floor. Given Libby's penchant for walks and struggles with striking out batters, he may be best served in the minor leagues or as a trade piece.

LHP Cooper Hjerpe

Cooper Hjerpe is the most junior of these options. He was drafted in 2022 and has yet to pitch beyond High-A Peoria. However, there is a lot to like about the deceptive lefty; while his fastball won't blow batters away, he is able to tunnel it well with his breaking pitches. Hjerpe looks to start 2024 in AA as a starting pitcher.

Hjerpe appears almost fearless with the way he goes right after hitters, and despite his unorthodox mechanics, he throws plenty of strikes that should keep him in a starting role.

In Peoria this past year, Cooper got off to a decent start. In 41 innings, Hjerpe had a 3.51 ERA, 1.24 WHIP, and batters had a .183 batting average against him. He struggled slightly with walks (25) but struck out batters at a strong clip (51 K's in 41 innings). He did have a minor elbow surgery in May, and that limited his innings total this past year. He made two final starts in September and didn't pitch beyond the first inning in either game. He requires some buildup to be a starter again.

It would be a long shot for Hjerpe to pitch in the majors this year, especially in the rotation. The only way I see him being a starting pitcher in St. Louis would be if the Cardinals experienced a plethora of injuries and underperformance. I could see him getting a taste of the majors out of the bullpen towards the end of the year or the playoffs, similar to Adam Wainwright of old or Andre Pallante from a few years ago. It is highly unlikely that Hjerpe will make the starting rotation in 2024.