I agree with those who say it's the linemen (and coaching stability). They just keep pounding and pounding. Most teams crack. The better ones don't. RBs? They may all be 4.6 (that's charitable), but they're also 5'10", 225#. And, they just keep hitting the hole hard. Now, add in an athletic QB from NCS like they did last year and you have further improvement. This year it will be back to the tried and true.