A's need a SS but get one that is controlled past 2021 (can flip DeJong if/when an in house option becomes viable), and is at a much more budget friendly salary. Rockies get their catcher of the future that they've not be able to draft and develop or acquire. Cardinals upgrade their lineup, rotation, and bullpen NOW, when they desperately need help, or at least soon when those players return from the IL. They get to try and convince Story to stay in St. Louis before the bidding for his services commences. Cardinals apparently were high on Soderstrom in the 2020 draft and almost took him over Walker, so this could also work with the Cardinals keeping him and sending Herrera to the Rockies if the Cardinals think Molina will stick around for another year or two and if the Rockies want a player closer to the majors.