I can blame Weeden and the coaching staff simultaneously for not attempting to stretch the defense, which afforded Atlanta's defense the opportunity to load the box against a hot running game without consequence, which led to short Cowboys drives on offense, which led to an depleted Cowboys' defense being on the field far longer than ideal, which allowed Atlanta to wear the defense down and create the comeback.
That's part on the game plan - the passing game plan was obviously very conservative - and part on Weeden's known limitations - the game plan was obviously designed with protecting him in mind. Everything is connected, it isn't just a simple "X did Y wrong" issue.
Related, a general observation that isn't exclusive to here, but one that bothers me - this idea that whenever something goes wrong with a football team that the blame is solely with the coaching staff and the players are exempt really bothers me. Sometimes, the players just aren't good enough, and that's perfectly okay to admit.