Another thing to consider is that pretty much the entire offense returns in 2013.
I agree with Able. The 2010 recruiting class was a colossal failure on defense, but Shannon landed some talented offensive players who will play on Sundays. The loss of Storm hurts. He would be the missing piece this year.
Penn is right that we don't have proven big play guys. That's the biggest hole right now.
A couple keys:
1) the running game and the progression of the offensive line. We should see less shuffling up front this year, so it's imperative these guys develop chemistry and consistency. This offense has relied on big plays the past few years, but the defense would benefit from an efficient unit that converts short-yardage.
2) Dorsett and Duke staying healthy. Those are the two true game breakers, and the element they bring would be difficult to replace.