Bryce Miller or Bryan Woo
Similar to Shane Bieber, I don't think Bryce Miller or Bryan Woo of the Mariners raise the Cardinals' ceiling for 2024 as things stand, but they are both high-upside arms who would at least be rotation upgrades and could emerge as legit dudes this year or in future seasons.
I still have my doubts that Miller or Woo will be moved by the Mariners, and I really don't think they trade Logan Gilbert, but if the Mariners want to upgrade their lineup and the Cardinals like Miller or Woo, the trade could be there.
I could see a world where Donovan straight up for Miller or Woo works out. Both pitchers would not be free agents until after the 2029 season, giving the Cardinals a ton of team control with both arms. Woo made 18 starts in 2023, posting a 4.21 ERA with 93 strikeouts in 87.2 innings. He is a primary fastball guy with a four-seamer that sits in the upper 90s, a sinker in the mid-90s, and a cutter in the high 80s, with a slider that he mixes in as well.
Bryce Miller had a similar level of success in 2023, posting a 4.32 ERA with 119 strikeouts in 131.1 innings pitched. Miller has a mid-90s fastball and sinker as well but relies on a slider, sweeper, and change-up as well. Neither of these guys should be expected to be front-end starters in 2024, but their cost is high because of the cost control and the potential they have long term.
Personally, I wouldn't make this deal as I am more concerned with the 2024 rotatoin than I am having a ton of control on a pitcher. Yes, multiple years of control would be nice, but the upgrade they really need is another guy they can rely on at the top of that rotation right now. If it did not cost Donovan or Gorman for one of those two though, I'd be way more interested.