Why the NFL's helmet rule won't be game-altering as feared

NEW YORK -- NFL owners alarmed the football world in March when they slammed through a rule that promised 15-yard penalties and threatened ejections for something that is entwined with the game itself: using the helmet in contact. Coaches freaked over how to rewire ingrained techniques. Officials worried about distinguishing incidental contact from illegal hits. Players were skeptical that the rule could change anything except penalty and fine totals.

In the ensuing months, however, league executives have worked to soothe those concerns and pull back on expectations for the rule's impact in 2018. Those who attended a May 1 meeting at NFL headquarters in New York were relieved to hear details…