You cannot lead with your head.. simple as that. The Rule is two part.. one defining the crown the other leading with the head.
Great play by Perry, except when he went to lower the boom, slide the head to the side and nail him.
I hate the rule, especially in light that it isn't reciprocated to protect the defensive players, but Perry should have adjusted his tackle.
This angle is hard, but the angle closer to what the Referee had, it is very clear that he lead with the head. Matters not the place upon the helmet that made contact, it was led with the head.
Was it the worst I seen, nope not even the worst I have seen not called. But it was leading with the head.
Now, honestly, the NFL should not have the rule on the books unless it is helmet to helmet, as it really is designed to protect the tacklers more so than the player being struck. I get it the lower levels, to teach, here, piss on it, you want to damage your neck, so be it.
Personally, the rules protecting the candy ass QB's are bullshit, but I can't fault the Referee (in this case) from enforcing the horseshit rule. The NFL is guilty there.. I think they want you to lay out the pillow first, fluff it than smack the QB.
"The oranges are dry; the apples are mealy; and the papayas... I don't know what's going on with the papayas!"