Two bright spots emerged from Troy Brouwer’s blindside hit on Derek Stepan in the third period of Wednesday’s 2-0 Rangers victory in Washington. First, Stepan returned to the game and said afterward that he was O.K., and second, the Rangers scrupulously followed concussion treatment protocol.

The N.H.L. ruled the hit accidental and declined to suspend or sanction Brouwer on Thursday. But that second point above shows how far the league’s teams have come lately in terms of concussion awareness

On Oct. 7, for example, another Ranger, Rick Nash, was visibly shaken by an elbow to the jaw from the Sharks’ Brad Stuart early in the first period of a game at San Jose. Yet despite that explicit sign that he was in need of examination for a concussion, Nash stayed in the game for the rest of the first period. To the Rangers’ credit, Nash was held out of the second and third periods. After the game he complained of headaches, and he has been out since. (Stuart was suspended for three games.)

That Nash should have been pulled off the ice immediately for examination has been a part of the N.H.L.'s official concussion protocol since March 2011, a regulation passed in the aftermath of Sidney Crosby’s head injury at the 2011 Winter Classic. But since then, only sporadically have teams strictly followed the protocol, which requires players showing signs of possible concussion to be taken off the ice to a quiet room for evaluation and, if they pass, permission to return to play.