Zack Thompson's very promising turn in the rotation

The young lefty has been much better of late, and there are good reasons for that.

I’ll confess to not being optimistic about Zack Thompson’s jump to the rotation. Yes, I was aware that the flaws and peculiarities of the automated ball-strike system at the Triple-A level were mangling his numbers to a material extent. I was also aware that he was experimenting with his repertoire and getting stretched out, and those things often don’t lend themselves to in-game success. Still and yet, I couldn’t ignore the brutality of numbers at Memphis during his conversion from reliever to starter: a 9.09 ERA across 32 ⅔ innings from early May through late June with 39 walks (!) against 38 strikeouts. The contexts are essential, but it’s hard to explain away that level of struggle. 

Supposedly, it was all with an eye toward 2024 and putting the 25-year-old former first-rounder in the mix for one of the multiple rotation vacancies that club would have going into the offseason. In reality it turned out to be a foundation for Thompson’s giving the club much-needed rotation innings, high-quality innings, in the second half. Before we get into how all that’s gone – swimmingly, as you’re probably aware – let’s consider all the toggling he’s dealt with in just his second big-league season. 

• Thompson  prepared for the 2023 season as a reliever and indeed filled that role in St. Louis for the first month-plus of the season. 

• On May 2, he was optioned back to Memphis and tasked with transitioning to a starting role, which he would remain in going forward. 

• In early July, he was recalled and told, nope, we need you in a relief role again. After making just three relief appearances in 19 days, he was sent back to Triple-A. He made one relief appearance for Memphis, was recalled, and made a relief appearance for St. Louis. 

• Two days after his last short-relief appearance for the Cardinals in early August, he was again moved back into the rotation, this time at the highest level. 

While not all of this whipsawing is entirely understandable, some of it is because of injuries and a trade deadline that sapped the rotation of Jordan Montgomery and Jack Flaherty. What’s important, though, is that Thompson has excelled in his month-long stay in the rotation despite all of it.