As part of this plan, the NFL is circulating a "teaching" video of "Browns receiver Josh Gordon leveling Ravens safety Ed Reed with an illegal crackback block."
NFL tells coaches to remind receivers about illegal crackback blocks
“The rule states it is an illegal crackback block if a defensive player is contacted below the waist within an area five yards on either side of the line of scrimmage, within close line play, by an offensive player who is moving toward the position from which the ball is snapped,” Johnson said. “An offensive player who is aligned more than two yards outside the tackle when the ball is snapped is prohibited from coming back toward the football and blocking low or hitting a player in the head or neck area. That was the amended rule change that we put in for the 2012 season.”
And so the NFL has thrown a bone to defensive players, with a reminder that the league office will crack down on offensive players, too.