Can this former first-round draft pick save the Cardinals' rotation?

Zack Thompson has never had an assured spot in his major league career. He made his debut for the St. Louis Cardinals on June 3, 2022, and he pitched 4 solid innings in relief against the Chicago Cubs, allowing just 1 earned run with 3 strikeouts and just 1 walk. The game was a blowout, so it was noteworthy that he was still able to pitch well despite the lack of a need for adrenaline.

He has been yo-yoed around as both a starting pitcher and a reliever and in both Memphis and St. Louis. Thompson's professional career has been anything but consistent. After being drafted in 2019, Thompson had a normal rookie season. He then was a victim of the COVID shutdown in 2020 and the subsequent lockout in 2021. His career is littered with instability beyond his own control.

However, he was instructed this offseason to prepare for a starting pitching role. For the first time in 2 years, Zack Thompson knew what his job would be. He would likely start the season in AAA Memphis, but his name would be one of the first called should an injury arise with the big league team.

That situation came to pass this past week. Sonny Gray, the team's ace and apparent savior, left Monday's game with hamstring tightness. The MRI indicated it was a mild strain.

Zack Thompson could now see a promotion much quicker than he expected. After two years of being pulled between the bullpen and rotation more often than a doll between two toddlers, Zack Thompson will get a consistent opportunity to be a starter in St. Louis.

Conveniently, Thompson has pitched a nearly identical aount of innings as both a starter and reliever in major league baseball. His stats are outlined in the chart below.

Those figures should muster up some concern among fans given the fact that Zack Thompson will likely be the team's fifth starter for a couple of turns through the rotation. While he is serviceable as a back-end starting pitcher, he has thrived as a reliever in the majors up to this point in his career. A 2.31 ERA with a K rate near 25% is strong for a reliever.

However, Thompson fared much better in 2023 as a starter than he did in his first opportunity in 2022. The sample sizes are minute in both cases, but in 2023, Thompson had a 4.57 ERA, and batters hit .264 against him. Once again, these aren't high-end rotation numbers, but they are solid back-end numbers for a 4th or 5th starter in most rotations in the league.

Zack Thompson's greatest calling card is his breaking ball. His curveball had a +6 run value last year according to Baseball Savant. It generated whiffs at a 22.9% clip, so there is room for improvement there, but the hard-hit percentage against it was only 25%. Thompson's fastball was an above-average pitch in 2022, so if he can regain confidence in his heater while maintaining his curveball in 2024, he has a potent one-two punch with those pitches.

I recently listed Zack Thompson as a player who can take off for the Cardinals in 2024. A more solid role for the southpaw will do wonders for his confidence. Perhaps all he needed was a bit of a push to reach his full potential.

He has fared quite well this spring. In just 5 innings, Thompson has allowed 2 runs and struck out 4 batters. He has a 3.60 ERA in 2 starts. It is likely that Thompson's innings total will escalate to make him fully prepared to start the season in the St. Louis rotation.

I'm not saying Zack Thompson will be able to capably replace Sonny Gray; that would be foolish to posit. Rather, I'm simply putting my faith in a back-end starting pitcher to provide depth and quality innings, something the Cardinals will need desperately in 2024, especially without their newfound ace.