Really? Care to cite the actual RULE?
Better yet.. Here it is:
It is an illegal "blindside" block if the initial force of the contact by a blocker's helmet (including facemask), forearm, or shoulder is to the
head or neck area of an opponent when the blocker is moving toward his own endline and approaches his opponent from behind or from the side.
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Jennings didn't hit the guy in the head or neck area.