3) Cardinals were unwilling to trade Matthew Liberatore for Juan Soto
Matthew Liberatore stayed put as well in St. Louis. The reason might be even easier to understand than Carlson or Walker.
Despite Liberatore, 22, pitching to a 5.33 ERA in 27 big league innings this year, he is a young lefty the Cardinals seem to want to keep around for depth purposes. They’ve battled through plenty of starting pitcher injuries all year long. Before landing Jose Quintana and Jordan Montgomery at the trade deadline, Liberatore was often one of the pitchers called upon to give them innings.
Even in a lesser role, if Liberatore was to find his way into the St. Louis bullpen later this year, he could have value for a team with World Series aspirations. While Soto would have been a direct upgrade over Carlson, St. Louis would have had to make an additional move to find someone to give them what Liberatore possibly can.
From a bigger picture perspective, he is still the best pitching prospect they have. The Cardinals aren’t quite as all-in as some other big league teams this year. Their trade deadline strategy hinted at wanting to keep the farm mostly intact.
On a team with a battered original starting five and some starting rotation holes for next year, St. Louis might have felt the need to keep one of their clearest options for the rotation around.