Forward Progress

Last night during MNF, I was disappointed to watch Adrian "Fumble and/or TD" Peterson have the ball stripped out of his hands by the Packers, who then ran it down the field for a touchdown. Although this was a bold move by the Packers, and understandably plausible given Peterson's propensity to lose the ball at critical moments, I have to admit I was confused because at the time the ball was stripped, four Packers were swarming over Peterson, driving him backwards from his point of forward progress.
This is a tricky issue, and one that the NFL is unclear on. The NFL rulebook cites a player as "down" when:

The runner's forward progress toward the opponents' goal line is stopped by contact with an opponent, with little chance to be resumed. The exact moment at which the player's forward progress stops is subject to the judgment of the officials.

Shouldn't the officials have seen that Peterson's chance of resuming forward progress was essentially nil, given the 900 lbs of Packer defense climbing on his back?
Often, during games, a runner will charge up to a point, and get stopped upright. Defensive players and offensive players slam into this scrum, attempting to push it forward or back. As soon as it is apparent that the player is not moving forwards, the officials blow their whistles like crazy and rush in to stop any shoving or fighting that seems to ensue from these moments.
But Peterson, being clearly pushed backwards by several Packers, heard no whistle, and got no reprieve.
I am not suggesting that Peterson did not fumble. The ball was clearly stripped out of his hands while he was standing upright, moving his feet. But the NFL rule book is too ambiguous on this.
Back on Sept. 13th, Kevin Smith ran up the middle for the Detroit Lions, was stood up and stopped advancing. A player for the New Orleans Saints ripped the ball loose of Smith's hands before the whistle was blown, and ran down the field with it. But the officials reviewed the play and ruled that because Smith's forward progress had stopped, the play was dead. Wasn't that exactly the opposite call than was made with Peterson? And in this case it cost the Vikings 7.

The NFL needs to clearly define this rule and explain it to their officials.


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