I don't think it's unfair to hold Rex to the same critical standard that Chip Kelly was held to last year. While Rex has a longer track record of success in the professional ranks with his "system", it's difficult not to argue that he values that system above tailoring a defense to it's strengths. Much like Kelly, Rex came into a town that was fairly successful on the side of the ball they purported to be an expert in. Much like Kelly, Rex's team underperformed compared to the recent past. If the Bills aren't back in the top 10 on D and make the playoffs this year I don't think it's an overreaction to call for his firing.