Attempting to define goaltender interference has been a major theme in 2017-18.
Another page was added to the book Saturday in Toronto after an apparent goal by Pittsburgh Penguins defenseman Brian Dumoulin was waived off due to an interference call.
Not only that, Dumoulin was sent to the box for bumping Maple Leafs goalie Frederik Andersen on the play.
The Penguins were unable to challenge, leaving head coach Mike Sullivan understandably flummoxed.
Several players and coaches have implored the NHL to clarify this rule before the playoffs, and this play will certainly leave many continuing to scratch their heads.