you both have it right to some extent, imo.
the regular nfl refs are ridiculed because they are old and flabby and when they miss a call, most of the time it's because they were out of position. in addition, the NFL rules are a bit convoluted so the refs bear heat often for its' interpretation.
the new refs are being ridiculed because they simply are not thoroughly familiar with the NFL rules. there are many rules differences of varying degrees between college and NFL - when these refs try to make sense of those differences, their hesitance, which is interpreted as incompetence, is easily noted.