Caldwell coached for two season under Quinn. Quinn was hired in 2016. The Lions were one year removed from going 11-5 and nearly winning that playoff game against Dallas. They then went 7-9 when Mayhew was fired. Had the Seattle game where they batted the ball out of the end zone and the phantom facemask hail mary gone their way, they would have actually made the playoffs that year. Anyways, I was in favor of sticking with Caldwell but was fine with hiring Patricia. There was no indication Patricia would have been this hated by the players. I don't think he was the same coach when he became head coach of the Lions vs defensive coordinator.
Vrabel, who was hired the same year, had one year as defensive coordinator and his defense was the worst in the league. Being a good head coach isn't just about offensive or defensive rankings.