I'd agree it's no surplus, but I'd still be into exploring the possibility of "selling high" on McGuire as an asset while bringing in a veteran back up catcher.
Not that I'm advocating going down this road, but it seems as though the receiver of choice for Ryu with the Dodgers was none other than Russell Martin. https://dodgers.mlblogs.com/notebook-the-ryu-martin-connection-continues-turner-update-6d1d1673d4c8