He has an incredible arm and plus power. His approach is... questionable. However, he has been an above average hitter at every level. Scouts also routinely say that his raw power is better than he's shown in games. Actually his profile is a lot like Sanchez before he broke out.
Alfaro AA line (167 games) - .273/.324/.449
Sanchez AA line (191 games) - .265/.335/.424
Catcher development is non-linear, as they say. You can't teach tools tho.