HalfSmokes is on the money here. There's plenty of blame to go around for that Super Bowl loss, but what did Quinn and Shanahan do after that? Shanahan went on to resurrect the Niners from bums of the NFC West to perennial playoff team with multiple Super Bowl appearances.
Quinn? Well, he treads water for a couple years and then gets fired in Atlanta after an 0-5 start. Then he goes to Dallas and his defensive unit beats up on a bunch of bad teams in the regular season, leading to a wild card loss wherein they give up 40 to an unproven quarterback. Last year's showing was a little more respectable, but there was a familiar story in the divisional round: Quinn's defense finally snaps in the last 20 minutes of the game and they lose in the 4th quarter.
That 2016 Atlanta team made it as far as they did on the weight of their offense, too. They were a high-scoring team with a defense that was just along for the ride.
Quinn was fortunate in that he coached the Legion of Boom in the early 2010s, and he's been living off of that ever since. Nothing about the performance of his defenses in Dallas or Atlanta says, "this guy ought to be a head coach again in the NFL."
