4 prospects the Cardinals must add to their 40-man roster to protect from Rule 5 draft

LHP Cooper Hjerpe

Last but certainly not least, Cooper Hjerpe is the name that I fear the Cardinals may leave off of their 40-man roster this evening, but I really do believe he should be among the names added.

Hjerpe, the Cardinals' first-round pick back in 2022, has been dynamite on the mound for them since they drafted him, but the problem is he's barely pitched for them. Since being drafted, Hjerpe has pitched in just 25 games, posting a 3.38 ERA with 127 strikeouts in 93.1 innings of work.

Hjerpe had an awesome 2024 campaign that saw him start 15 games, striking out 76 batters in 52.1 innings with a 3.27 ERA between High-A and Double-A, and opposing hitters have a sub-.200 batting average off him for their career. Hjerpe doesn't blow you away with velocity, but his funky delivery and release angle allow him to attack hitters with great deception, and he's got some of the best strikeout stuff in the Cardinals' system.

Unfortunately, on top of the various injuries Hjerpe has experienced in his career thus far, he's currently rehabbing from Tommy John surgery and isn't expected to be back until sometime into the 2026 season. As I stated earlier, the Cardinals already have some rehabbing arms on their 40-man roster in Tekoah Roby, Tink Hence, and Sem Robberse, so the club may not want to have another arm taking up a spot like that.

But man, Hjerpe's stuff is just too good to give up on already. I still believe he has a bright future as a starter, but even if he can't stay healthy enough to do that, he could become a very valuable reliever going forward. Heck, even in 2026, I could see the Cardinals using him in that role to make the most of his 40-man spot and to develop him against high-level hitters while not wasting bullets in the minor leagues.

We are about to find out a lot about how Bloom's regime sees a player like Hjerpe. While his injury may cause other organizations to back off of him, I have a strong feeling that Hjerpe would be a top target of organizations that develop pitching well.