Frazier is in charge, yes. It’s also true that he and McD believe in the same defensive principles which is part of the reason Frazier is the DC; that and his HC experience, which was valuable for McD. Firing Frazier would be like firing himself. That’s why it’s not a real conversation for fans to engage in. It’s just a fever dream.
A real convo to have is how can they adjust their principles with the talent on hand or who can they add, and how, to help the defense? A wholesale change of defensive scheme would probably necessitate changes in personnel and that ain’t happening in one off-season. On a whole that could seriously set the team back even further.
I get why people are pissed; I am too. But if you’re on watch for a coordinator firing you most likely will be watching for at least another year.