First of all, let me say that I was rooting for Carolina yesterday; I had a bet on Carolina yesterday, so don't think that this is sour grapes in any way.
"The ground cannot cause a fumble" rule makes no sense. Look at the play in the 4th quarter yesterday. Carolina receiver Steven Smith is hit and the ball pops loose and is recovered by the Eagles.
But wait. The play is reviewed, and it just so happens that the replay shows that his knee touched the ground a milli-seceond before the ball popped out. So the ruling is "no fumble".
Clearly, on this play, it was the hit that caused the fumble, not his knee touching the ground.
It is the job of the receiver or running back to hold onto the ball. Period. A fumble should be a fumble, even if he hits the ground first.