On one end you hear "We won 10 games, we should be happy with that!" from some people and "We completely mismanaged the end of game (or half) with poor clock mgmt and poor play calling!" from others and both have some basis in reality.
And that's ok. What often fails to take place is a subsequent deeper dive. Why did that play get called? Maybe the right play was called and the defense made a play and it wasn't on the OC....but if the guy calling out poor play selection doesn't know enough to recognize that, his argument falls flat. Similarly, while 10 wins is overperforming expectations it doesn't negate the fact that 11 or 12 were entirely possible with literally one or two differences in each game that the OC could have controlled.*
Maybe some people get anchored in their opinions based on identity. That certainly happens a lot in politics and religion, so it's not surprising to see it bleed over into sports. And maybe sometimes that anchoring is well-intended. Much of the time I suspect it's rooted in a lack of education or understanding. Regardless, it's as I said - some people don't want to have a cogent back and forth. Just huck the color mud that reflects their opinion.
*You can make a valid argument that the difference between 10 and 12 wins was more on the shoulders of the QB than the OC, but that's another argument that people have strong opinions on and often can't get past their opinions long enough to see the validity in the other viewpoint.