I said before the playoffs started that I got the sense that Quinn had peaked here, and that he probably felt similarly, which is why he'd be more open to HC openings.
He adjusted his scheme a good bit after getting fired in Atlanta, and he got a bit lucky falling into a talent like Parsons, but I think the league has started to pick up on how to attack what he's put together here. I'm fine keeping him another season just because it may be a lame duck year and he's still a solid DC, but the guy shouldn't be in any HC conversations given how this past season ended.
And it wasn't just the Green Bay game, the defense was too boom/bust all year, they were either getting splashy turnovers/sacks or teams were slowly driving the ball on them as the defense kind of gave up free 4-5 yard chunks at a time.