stating that Mike Williams is a better closer is not a knock against Williamson from my part and certainly doesn't mean that Willy isn't a good reliever or that he can't blossom in the closers role. It's just an argument based on statistics.
Williams saved 46 games last year with only 4 blown saves.
Williamson blew already 4 saves in only 12 chances last year. He has much more to prove than Williams and even his high K-rate and his low ERA doesn't neccessarily make him automatically a good closer.