Detroit Lions
By most franchise standards, Jim Caldwell had a middling record. But the Lions find new and innovative ways to hurt their fanbase every year. At least Caldwell guided them to the playoffs a couple of times and left with a winning record. We’ll give Dan Campbell an honorable mention for revitalizing Detroit (via Detroit Sports Nation).

There were plenty of awful Lions coaches over the years. Matt Patricia arrived with a big reputation as a defensive coach. But the Lions had the weakest defense in the league during his tenure. Nonetheless, Marty Mornhinweg is their worst coach of the modern era. Remember when he chose the wind instead of the ball against the Bears?