The NFL continues to fire coaches who do not reach the playoffs. When you think about it this is pretty absurd given the fact that the are a few elite teams in the NFL and the majority of the remaining teams are just plain bad. This speaks to the talent level, and in reality very seldom the coach. New coaches are brought in each year and the ones that are hired are given little time to produce a winner.
It will take time for any new coach that is hired as a replacement to make an impact, meaning actually win some games, let alone make the playoffs. The Eagles Chip Kelly was successful in his first year, making the playoffs and winning his division, but this is certainly not the norm for a new NFL coach. Kelly without a doubt is a rare exception.
The reality is what is the available talent level when looking for a new coach? How likely will a new coach win and make the playoff in one year? Someone will have to serve as a scape goat and get fired so others can keep their jobs. That's how the American workforce including the NFL works. If you don't win, even after one bad year, you're out. Example, Tampa Bay's Greg Schiano. He should not have been hired in the first place. He did not have clue as to how to perform his job. On the other hand Chip Kelly is definitely an exception. One in a million. He made an awful lot of teams look really, really bad. Everyone needs to copy his offense and find a defensive scheme to stop him. Chip Kelly made Nick Foles look like a 20 year NFL Hall of Famer. In reality he is not. The credit goes to Chip Kelly and his innovative play calling and spacing.