The players have to execute. The blame is on everyone, including Josh. Just like the credit for success falls on everyone. When we win, it isn't only because of the players. When we lose it isn't only because of McDermott. They all play their part.
I didn't see anything in that game that points me to believe that there was some epic coaching failure. The Bills got beat by injuries, heat exhaustion, and failures of execution (which does fall on the players, because clearly the coaches did their jobs and the players didn't execute).
The only thing I fault for the coaches is playing Moss too much. But that is a game where you need all of your depth because of the extreme conditions, so if there is ever a game where Moss is going to share the load, that was the one.