Zach Thompson is the Cardinals best left-handed reliever
Coming into the 2022 season, the St. Louis Cardinals were hoping to have repeat performances from left-handed relievers T.J. McFarland and Genesis Cabrera, both of whom played major roles for the club in 2021. But by season's end, McFarland had been released and Genesis Cabrera was trying to fix himself in Triple-A Memphis. It was rookie Zack Thompson who had now filled that void and done so exceptionally well.
While Thompson came through the organization as a starting pitcher and likely hopes to factor into the rotation long-term, he is easily their best option from the left side in the bullpen in 2023. Thompson's 29.2 innings of relief in 2022 show him post a 0.91 ERA. His curve spin rate ranked in the 88th percentile on the season, and with good fastball velocity, Thompson had weapons that could be used to get big outs late in games.
St. Louis did just sign lefty Andrew Suarez to a minor league deal, and guys like Cabrera, Packy Naughton, Matthew Liberatore, JoJo Romero, and Connor Thomas could all factor into the bullpen as left-handed options during the season. But barring a signing of a reliever like Andrew Chafin or Matt Moore, Thompson is the Cardinals' best bet out of the bullpen when it comes to southpaws.
There's also not really a path toward the rotation either. Outside of the five projected starters, I would guess Dakota Hudson, Andre Pallante, Gordon Graceffo, Thomas, and Liberatore would all receive looks before Thompson.
Thompson being their best left-handed option in the bullpen also makes him one of the most important relievers they have in 2023. Thompson was very good in 2022, and they'll need him to be good once again, or they'll risk not having the kind of firepower necessary to shut down elite left-handed hitting late in games.
Thompson is not just a left-handed specialist though. While he held hitters from the left side of the plate to a .372 OPS, right-handed hitters had just a .176 average against him as well. They did slug off him much better though, but that shouldn't stop the Cardinals from using him against both-handedness. With the three-batter minimum, having guys who can face both sides of the plate is crucial.
If Thompson cannot fill the left-handed void out of the bullpen for St. Louis, the club better hope one of their other options can. But for the time being, Thompson should give the Cardinals stability in the pen for 2023.