This is insurance. Nido is out of options. Once Navaez returns, there's a chance he'll be lost. His hitting is pathetic, but he's considered a good defender, so another team may snatch him up. They'll need someone at Syracuse who can be called up if Navaez or Alvarez gets hurt. Sanchez has caught in the majors (not well, but still), so he's worth keeping just in case. None of the other AAA catchers look like they can hit (they're not hitting in the minors).