Tier 3: Back-of-the-rotation starters or pitchers looking for "prove-it" deals
Free agents: Shota Imanaga, Michael Lorenzen, James Paxton, Kenta Maeda, Frankie Montas, and Luis Severino
Trade: Jose Quintana, Jeffrey Springs, Clarke Schmidt, and Paul Blackburn
Unlikely: Jack Flaherty
So the Cardinals have added their ace to headline their rotation. They signed a number two/three starter or traded for a young pitcher with upside. Now what is left to do is grab the third starting pitcher that they wish to add to their rotation, who should slot in either as their number four or five starter next season.
On the free agent market, Shota Imanaga is a left-handed starter from Japan who many speculate could be posted this coming offseason. He'll cost far less than Yamamoto, probably looking at somewhere between a $12 million and $16 million AAV over 3-5 years. The Cardinals have already scouted Imanaga, and he would be a high-upside fit for the back of their rotation,
Michael Lorenzen is probably somewhere between a tier 2 and tier 3 guy for me, but I put him in this category as I think he goes for below the market value of the tier 2 guys, functioning as a low-end three or high-end number four starter.
James Paxton and Kenta Maeda are both guys who have strikeout stuff, are in their mid-30s, and have been a bit inconsistent in both performance and health over the course of their careers. Both could pitch up from their role as a number four or five starter or could miss significant time with injuries. But if you want any kind of upside from a player on the low-end deals that they'll be getting, you're going to inherit that kind of risk.
Frankie Montas and Luis Severino are interesting arms as they would likely seek one-year deals with a decent AAV, hoping to recoup their value as middle-of-the-rotiation or better starters and get larger deals the following offseason. If their markets do not develop, they could be intriguing buy-low candidates for St. Louis. I doubt Flaherty comes to St. Louis as the deal he gets in free agency will likely be more than they are willing to pay.
On the trade market, a Jose Quintana reunion has caught steam amongst people who are speculating about the Cardinals' pitching targets, as he would not cost much in terms of prospect capital and the Mets may even be willing to eat some money on his deal to make him even more affordable. Jeffrey Springs would be coming off a season-ending injury for the Rays and may not be back until a month or so into the 2024 season, but he can pitch like a number two starter when he is right and healthy. He is locked into a multi-year deal though which leads me to believe he may not cost a ton.
Clarke Schmidt seems like a natural fit for the Yankees if they reengage on Dylan Carlson or Tyler O'Neill trade talks this offseason. He's a number four starter at best for you but will come at a low salary and room to develop still. Paul Blackburn is another guy who projects to be at the back end of the rotation on a cost-controlled deal.
The Cardinals have publically stated their goal to get three starters this offseason. As long as they get a guy from each of these tiers, the numerical goal will meet the quality needed to get back into contention in 2024.