Boston’s slumping top line needs some punch. But not the kind of cheap-shot foolishness Brad Marchand was guilty of Tuesday night.

Long known as one of hockey’s great irritators and agitators, Marchand sucker-punched a kneeling and unsuspecting Scott Harrington in the back of the head during a stoppage of play in the Bruins’ 2-1 loss to Columbus. To compound the crime, he quickly skated away, using two other players as cover for his misdeed.

It was unneeded, craven and dangerous. It, however, was both in character and unpunished.

The officials were busy breaking up a scrum, so they never saw it and it drew no penalty. The NHL’s Department of Player Safety looked into the incident, though Sportsnet’s John Shannon reports that Marchand will not face any supplemental discipline, saying the matter will be handled internally.

“I’m not giving you my thoughts,” notoriously salty Columbus coach John Tortorella told reporters when asked about it afterward. “I don’t need to give you my thoughts on that.”

Marchand has a long history of bad behavior, having been suspended a half-dozen times and fined three more. Still, Boston coach Bruce Cassidy had defended Marchand, including after the latter’s stick-snapping incident in Game 1 against Columbus.

“Marchie’s a competitive guy. I think that narrative gets out there,” Cassidy said, according to the Boston Herald. “Marchie had no penalty minutes in the playoffs before [Saturday] night. None. Zero. Leading scorer on our team. All of a sudden I’ve got people in the NHL [saying], ‘Keep an eye on him.’ What are you talking about? Why are you going down this road on a guy that’s kept his nose clean?”

Boston is trailing the series 2-1, and Marchand hasn’t notched a point since Boston’s Game 6 against Toronto.