The current 2019 infield, not including C or 1B, looks something like:
2B - Biggio
3B - Guerrero
SS - Bichette
2B/3B - Drury
SS/2B - Urena
I'm pretty sure this move was made with an eye to the fact that Drury and Urena are both a) controllable and out of options next season. If the FO saw value in an external backup infielder, it's hard to imagine a better fit than the guy they just gave away for nothing.