Can someone explain to me why the Giants, and most fans, and all sportswriters seem to think Eliezer Alfonzo is not a viable first-string, everyday catcher?

Has he failed at something? Hitting, pitchouts, blocking balls? I just don't understand it. Reading the Merc this morning I saw this sentence reading something like "With Matheny's career likely over, the Giants are in need of a catcher." And it went on for a few grafs about Bengie Molina. The word "Eliezer" never appeared. Why is this? I'm starting to feel like I'm the only one on Planet Notgardo and everyone else doesn't believe the planet exists! Help a sister out.