Andrew Knapp, from the University of California, performed well and has the added benefit of being a switch-hitter, which helped make him attractive.
Knapp also doesn't have a lot of mileage on him as a catcher, which can be good and bad. The bad part is that it's going to take him a little more time to develop defensively, although the Phillies see his defense as a diamond in the rough. The good part is that the Phillies can have their people work with him before he's gotten into too many bad habits. While there's going to be a learning curve, Knapp is known to have a strong arm and quick release, which should help cut down baserunners.
Prior to moving behind the plate, Knapp played some outfield and first base at Cal and has performed well offensively. Knapp had an impressive showing in the Cape Cod League last summer and has the ability to hit for both average and power.
Right now, Knapp is a hitter who catches, but with more work behind the plate, his defense will improve, it's just a matter of by how much.