It sounded like FSU was one of our opponents that did not stack the box. I didn't see the game yet, but apparently they left the safeties high. Kelly said we can and will run against that.
FSU probably convinced themselves that they were a good run defense and did not need to stack the box against ND. Horrible coaching, since we had our weaker passer and better runner in at QB.
Other teams will stack the box again, mostly because nobody likes to be beaten on the ground. They'd rather force Book or Wimbush to make plays.