Cardinals promote pitching prospect Zack Thompson, designate IF Kramer Robertson

The Cardinals announced a series of roster moves Friday, most notably selecting the contract of 2019 first-rounder Zack Thompson, who’ll join the pitching staff with the Cards slated to play four games in the next three days. Infielder Kramer Robertson was designated for assignment in a corresponding 40-man roster move. The Cards also optioned lefty Matthew Liberatore and right-hander Kodi Whitley to Triple-A Memphis and recalled righty Johan Oviedo from Memphis. Furthermore, the Cardinals announced that outfielders Tyler O’Neill and Dylan Carlson will begin minor-league rehab assignments — O’Neill in Triple-A and Carlson in Double-A.

Thompson, 24, was the 19th overall pick in 2019 and has ranked among the Cardinals’ best pitching prospects since being selected that day. He’s not as highly touted as Liberatore, who was just optioned out, but ranks 15th in their system at Baseball America and ninth at MLB.com. The lefty saw his stock drop in 2021, when he posted an ERA just north of 7.00 and walked 12.8% of his opponents in Triple-A. However, that came after an aggressive jump from Class-A Advanced, where he’d thrown just 13 1/3 innings, and on the heels of a year-long layoff from pitching in a game setting due to the canceled 2020 minor-league season.

Thompson has gotten out to a much better start in 2022. He’s still far from dominant in Triple-A but has worked to a 4.67 ERA in a hitter-friendly setting while sporting dramatically improved K-BB numbers. His strikeout rate is up from 18.5% in 2021 to 30.1% in 2022, while that 12.8% walk rate has been curbed to a very solid 8.1%. He’s induced grounders at a 44% clip — very slightly above the MLB 43.1% average — which should pair nicely with the Cardinals’ elite infield defense.

Scouting reports on Thompson note that his velocity took a step back in early 2021, though BA notes that it improved over the season. At his best, Thompson sits in the low 90s but can reach back to dial it up as high as 97 mph on the radar gun, and both BA and MLB.com tout his plus curveball and its elite spin rate. If he’s back on track in terms of velocity, there’s a chance for Thompson to eventually settle in as a mid-rotation starter in St. Louis, where the team’s overall defensive mastery can help to boost any pitcher’s raw run-prevention numbers.

Injuries to Jack Flaherty and Steven Matz have thinned out the St. Louis rotation at the moment, so Thompson could parlay this first big-league look into a more prominent opportunity if he impresses early on. Looking forward, Adam Wainwright is only on a one-year deal, and it’s not clear what the future holds for him. Thompson and Liberatore could be vying for permanent rotation spots alongside Flaherty, Matz, Dakota Hudson and Miles Mikolas before long, now that both have reached the Majors for the first time.

From a service time vantage point, Thompson’s promotion comes far too late in the season for him to accumulate the service time needed to reach a full year in 2022. As such, the earliest he could potentially reach free agency would be after the 2028 season. If he sticks in the big leagues from here onward, he’d likely reach Super Two status and be arbitration-eligible four times rather than three, but one look at the manner in which Liberatore has already been shuttled back and forth a few times suggests that Thompson could be handled similarly.

As for the 27-year-old Robertson, he was selected to the 40-man roster back in early May but appeared in just two games before being optioned back to Memphis. Robertson went hitless in his lone plate appearance, though he did pick up an RBI. The 2017 fourth-rounder is a career .242/.367/.396 hitter in 222 Triple-A games and has routinely turned in elite walk rates throughout his minor-league tenure. He’s never hit for a high average or displayed much power, however, and he’s been primarily a second baseman and third baseman rather than a shortstop, which curbs his appeal as a utility option. Robertson does have all three minor-league option years remaining, so it’s possible another club will look at that and his gaudy OBP marks and see some optionable infield depth.

The Cards will have a week to trade Robertson or attempt to pass him through outright waivers, at which point all 29 other clubs would be able to place a claim.