Every sports fan has a tendency to overrate his own team's talent and underrate the talent of other teams. Many times we've heard some fan proclaim, "The Cowboys have the best O-line in the league!" when, frankly, calling the Dallas offensive line "Top-10" would be more like it. The same fans sometimes also call Dez Bryant the best receiver in the league - again, he's in the Top 10.
On Thanksgiving, we saw the reality. The Cowboys' line surrendered 4 sacks, Murray gained only about 70 yards, and Dallas managed just ten points at home against Philadelphia.
Perhaps the unpleasant truth is that this offense cannot just impose its will on anyone it wants. It cannot just operate by giving Murray 30-35 carries a game and bulldozing every defense into submission. The Cowboys certainly ought to keep trying that tactic as long as they can, but it's not foolproof or invincible. December will tell.
Dallas has four games remaining to once again try its hand at the steamrolling offense that worked so well for it in Weeks 2-7. If it fails to work, then it's either Romo having to air it out 30-40 times a game - which sure didn't work out well in 2011, 2012 and 2013 - or season over.