A new rule makes it illegal to land with full or partial body weight on the quarterback when he is on the ground.. Defensive players believe that they are being asked to alter the pass rush motion they have done their whole careers and pull back in the middle of action. Losing a starting QB has such a profound impact on a team that the NFL believes extraordinary measures were needed to protect quarterbacks. I believe that the League told officials to enforce the rule zealously at the start of the season to send a dramatic message. It is an attempt to alter defensive players' behavior.

Source: Forbes September 28, 2018 20:29 UTC