My choice is Philbin and Gase. For years I've said that Philbin was the worst thing to ever happen to the Dolphins, and then Ross hired Gase, a man who made Philbin look almost competent!
Philbin took over a tough team that could compete with top teams, but usually lost because they lacked talent at the offensive skill positions and had to settle for FGs instead of TDs. Instead of fixing that problem by adding talent, Philbin neutered a decent defense and built a "finesse" o-line that couldn't protect their QB even with several 1st round picks on it. He described his offense as being dynamic, explosive, and high-scoring. But, this short pass based offense with little to no running game was as dynamic as molasses; Philbin's teams seemed unprepared at the start of every game and usually couldn't score until nearly half-time, and by then they were behind several scores. This slow moving offense which seemed to always have the team trailing the opponent was coupled with a defense that was built to play with a lead... which they rarely ever had! Also, even when Miami wasn't very good, they usually beat the Jets and the Bills... until Philbin ruined the team. Under Philbin (and then Gase), Miami's o-lines were consistently pushed around and dominated by the d-lines of New York and Buffalo. Philbin took a team that was a few key players away from being a playoff team and ran it into the toilet. I think it was 2013 when Miami had two games left against the Bills and the Jets, and all they had to do was win one and they earn a Wild Card berth. Philbin's team went 0-2, scoring just 10 total points in those two games!
Gase, like Philbin, placed little emphasis on the running game, preferring to use RBs as receivers out of the backfield. And, instead of replacing Philbin's weak o-line, he kept it. The only thing Gase did well was to run some creative trick plays that usually worked. However, when it came to "regular" playcalling he was a complete idiot. He must have thought he was a genius, because he'd call plays with the least chance of success probably thinking that the opponent would never expect that! Gase's offense (like Philbin's offense) struggled to convert 3rd or 4th and short on the ground because his o-line was weak and couldn't block, and he loved calling those short passes. Here's a sampling of Gase's playcalling: On 3rd and 10 most teams would throw an 11 or 12 yard pass, but Gase's offense would have several receivers running 5-8 yard routes with a completion resulting in a 4th down punt. On 3rd and 20, Gase seemed to always call a run up the middle for 2 or 3 yards. On 3rd or 4th and 1, most teams can run it and get the 1st down... but not Gase. His favorite play of all in this situation was a throw to a RB or WR behind the line of scrimmage who was then immediately tackled for a loss because the o-line couldn't block anyone!
