The roster is the by far and away the biggest problem, not the coaching. This is a garbage dump that Macc assembled, and I have no idea why he still has a job, unless he was directed by ownership that he had one year to build a competitive roster (in 2015), which was likely the case.
Macc inherited a bad situation, in that the Jets had a ton of money in the 2015 offseason. You don't want to have a massive amount of cap space when that money is not going to be used mostly on extending your own players. Otherwise, you are going into the offseason with the intent of using a huge amount of money on poor value free agents acquired through auctions, and mostly those who are vastly overrated in the league despite being available at the right time. Getting a bunch of over 30 fading veterans and putting lipstick on the pig (or Fitzpatrick's beard, in this case)...this collapse was coming.
I know Jets fans hated Idzik, but I thought the fans were impatient. He whiffed on some draft picks and talent evaluations, but too small a sample size to know if it was just bad luck. It was a massive rebuilding project that required patience, developing young players, and resisting the temptation to build a quick fix team. Then Johnson pulled out his trademark card of, after two years, starting over with an opposite philosophy, bringing in the low key Bowles to replace Ryan and the spend happy Macc to replace the conservative Idzik. I see a pattern with the NYJ...