MLB.com scouting report;
While Tait’s overall defensive game is a work in progress, there's reason to believe he’s headed in the right direction after showing a lot of improvement behind the dish last year. He sets up well and his receiving has gotten better to the point where they think he could be an average defender in the future, pairing nicely with his plus arm. If that keeps trending in that direction, Tait should have no problem being a big league regular catcher in the future.
FanGraph's preseason scouting report;
Tait is still not a great defender, but he's gotten better each year. His receiving around the edges of the zone has improved substantially as he's climbed the minors, and he's athletic leaving his crouch and firing from all kinds of awkward platforms. He's not an especially good ball-blocker right now but, overall, this is a good spot for a teenage catcher to be.
Doesn't sound like no potential on defense to me...