Jose Fermin
Jose Fermin was recalled along with Nick Robertson when Zack Thompson and Jordan Walker were demoted to AAA Memphis. Fermin can play across the infield, and his defensive abilities are at least above average at second base and shortstop. His hit tool has played well in the minors, and his speed projects to be above average as well.
Fermin started off hot this year with Memphis; he was slashing .350/.458/.650 with 4 home runs and 5 steals. He provides capable defense at multiple infield positions, and his strong numbers in AAA provided hope that his second appearance in MLB would go much better than his first. He finished 2023 with a .235/.339/.255 with decent walk and strikeout rates.
Fermin's inclusion on the roster already is questionable given the fact that he sits third on the depth chart at shortstop behind Masyn Winn and Brandon Crawford, third at second base behind Nolan Gorman and Brendan Donovan, and third at third base behind Nolan Arenado and Nolan Gorman. There aren't many lineups where playing Fermin makes more sense than somebody else.
Once players like Matt Carpenter, Tommy Edman, and Dylan Carlson return, Fermin becomes even more unnecessary in St. Louis. he would likely be demoted to AAA Memphis rather than DFA'd, however. He has played in only 2 games this year, and he has yet to record a hit in 3 plate appearances. Fermin's call-up in the first place was curious; if he were to be on the roster beyond May, either injuries hit the team hard, or he's playing so well that he displaces the next player on the list.
Personally, I would prefer to see Fermin get more run as the backup shortstop rather than Brandon Crawford, but that's unlikely to happen.