I don't believe helmet to helmet contact is a penalty between a runner and a tackler.
It's only helmet to helmet between tackler and defenseless players (i.e. catching the ball) or qb's that gets flagged.
That's why pierre thomas getting his face demolished by whitner wasn't a penalty.
Guess I could be wrong though, they try to get so specific with rules these days and it just leads to a more confusing, controversial outcome. A perfect example of this is contact between ball and ground on a catch. I think if the ball touches ground before possession is maintained, no catch. All this "well it moved" "he had control through ground" bull shite is getting old. Just have clear cut rules and deal with the downside of that imo, at least that way it is the same for everyone
This post was edited on 1/14 at 5:45 pm