Yes, John Fox is specifically telling his players to keep the game close. That's right, he's personally responsible for any lead that the team may relinquish. No, don't give credit to the other team, it's all John Fox's fault that the game works that way.
Trying to run up the score can be a double edged sword. You don't do it unless you know you're going to get points out of it. Sure, Jerome Bettis fumbles don't happen often, but there's always the chance.
All it takes is one play for the tide of the game to turn. And seriously, if they wanted to score, they would. But there are other factors to how the offense works.. for example.. the other teams defense?