When an NFL head coach is fired, sometimes people tend to use the same thought process as George in a classic Seinfeld episode. Since the head coach who got fired was the wrong guy, the right head coach must have the exact opposite traits. Because Rex Ryan is a defensive oriented coach, many want the Jets to replace him with a coach who has an offensive background.
I can understand the thinking, but I'm not sure I agree. It's true Rex Ryan failed to build a quality offense with the Jets. I don't think that means every head coach with a defensive background will also fail to build a good offense.
Consider this. Peyton Manning, Tom Brady, Drew Brees, Tony Romo, Ben Roethlisberger, Andrew Luck, Russell Wilson, and Matt Ryan all developed under head coaches with defensive backgrounds. A coach need not be an offensive guy for his team to build a good offense.
There's a lot more to being a head coach than just making one side of the ball work. Rex showed us that. Coaches need to build a quality staff to compensate for their weaknesses. They need to develop talent. They need to motivate and inspire players to put in the work. They need to supervise and refine the game plans of their subordinates. They need to be able to manage the game effectively from the sidelines. History shows successful coaches who do these things come from both sides of the ball.
The right guy for the Jets might well be an offensive mastermind. Personally, I am very high on Auburn's Gus Malzahn. The Jets could easily find that their right guy is a defensive coach. Don't hold the sins of Rex against every defensive coach. Rex might not have been able to make the offense work, but that doesn't apply to everybody.