Look, let me start by saying it is just not a thing that the NFL is rigged. This is not about a grand conspiracy; this is about the fact that fans are increasingly irritated with officiating. Part of the issue is the rise of replay and other technologies in sports that make it so yeah, after the fact it is almost always possible to know what a call should have been.
Combine this with the lack of consistency in application of the rules, or the trend in professional ranks of protecting big stars (how do you even record a legal sack anymore?