I'm starting to talk myself into Arenado....plus. Hear me out for a second.
Two successive years of rotten infield defense made it my top priority coming into the season, and they have done nothing to improve it. At worst, Arenado is a plus fielder moving a minus fielder (Devers) to DH. He's played with Story, and this young team could use another veteran.
Cards are desperate to deal him and should take Yoshida back--after all, Bloom signed him. And he'll hit in a big ballpark like STL. A straight swap saves STL $15-20M. But I would give more to get back one of two players--Ryan Helsley or Ivan Herrera. Helsley had 49 saves and a 2.04 ERA last year, but makes $8M in his last arb year and the Cards aren't a contender. Their SPs are old; a young starter like Fitts or Priester might land him.
Herrera would cost more, but I'd deal Crawford (who would thrive in that big park) for him - a 24-y.o. catcher who hit .301 with an .800 OPS last year. Very valuable but STL has many young catchers and needs starting pitching.
Arenado improves the defense (a lot), balances the lineup, offloads Yoshida (who I like but he's a bad fit), and gives Campbell more time to develop. Even if his bat suffers, his glove makes it worthwhile with this ground ball heavy staff. Contract can be dumped by 2026.
Arenado-Helsley makes them competitive with BAL, NY. Arenado-Herrera sets them up for the future.