CDD has to know his seat is warming up with the loss to KY. That said, I wonder if he's trying to buy an extra year if next season goes off the tracks again? If little improvement is made in the running game next season, he could throw Hiestand (and maybe Chaney) under the bus and clean house. His offensive staff could potentially be his escape-goat get-out-of-jail-free card.
If he were to let Hiestand or Chaney go now, and then the running game continues to suck in 2012 under a different coordinator/OLC, you have to figure he'd be a goner for sure - a la Fulmer after the Clawfence disaster of 2008.