This erosion is well documented as being across all of society, in research on the impact of social media, and the harnessing of it for commercial and political agendas. We are literally losing IQ points (although there's a lot of good research on that being at least in part linked to chemical poisoning.)
Sports in general, and football in specific, are just caught up in that wave. Plus, the tribalism of sports tends to heighten it.
But on the topic of the Giants, why in the world would a head coach fire defensive assistants that work directly for the DC? That's nuts. Sports organizations are so weird.