I really want Castro. I think he's my favorite offensive player to add by an order of magnitude.
He's not an especially good hitter, I think it's probably good to calibrate expectations properly that he's a league average hitter that has just gotten some good fortune in the BABIP department the first half of this year. But man that versatility is attractive.
If you read the Athletic article from earlier in the week about adding a bat, it's clear that the thinking is as much about reducing risk as it is improving the team. Fans are focused on upgrading from Shaw and Turner, but just as important is future proofing such that an errant fastball to Nico Hoerner doesn't torpedo our middle infield. Castro is perfect because he does both by virtue of playing literally anywhere.