The sad saga of Marc Trestman's second year goes far beyond his win-loss record, which is bad. The 2014 Chicago Bears have talent, but they are an absolute mess. Has any NFL coach ever thrown his offensive coordinator under the bus as he did last week? He has completely lost control of the locker room, and it shows in the field. He's supposed to be an offensive genius, but he can't call plays to take advantage of his team's strengths. He has to go.
The Bears defense has been a liability the last few years. This is no surprise. Marc Trestman was hired to be the offensive guru and make Jay Cutler into a really effective quarterback. The fact that their offense, and Cutler in particular have been so bad is a sign that they need a new coach.
How long has he been the coach? Is that the only reason they would fire him? If he has been there a while, I know the bears have had some great seasons, so no. If he is new then maybe he needs some time to bond with the team and figure things out.
A losing season cannot be blamed solely on the coach any more than it can be blamed on any one player. A team must take their successes and failures as a unit, not divide against their coach. In the end, the players on the field are the ones responsible for any losses.