It's the kind of traumatizing event no hockey player wants to witness; the Montreal Canadiens' Brendan Gallagher has been on the ice for two of them in the space of seven months.
During last fall's NHL lockout, Gallagher was playing in the Bell Centre with the AHL Hamilton Bulldogs against the Syracuse Crunch when teammate Blake Geoffrion was pasted near the far boards, suffering a skull fracture that has, in all likelihood, ended his career.
On Thursday, Gallagher was on the same rink when Ottawa Senators defenceman Eric Gryba hit teammate Lars Eller with an open-ice hit as he readied to take a pass in the middle of his own zone, sending the Dane crashing to the ice.
He would leave on a stretcher, and spend the night in hospital with facial fractures and a concussion.
"It's not fun. Whenever you see a guy carted off like that, it puts things into perspective. It's scary," Gallagher said afterward.
Gryba faces a hearing with league disciplinarian Brendan Shanahan at noon on Friday, the incident is instructive.
At root, it's a question of historical interpretation.
And it illustrates how both how far the NHL has come and how far it needs to go.
After the game, Ottawa coach Paul MacLean, a veteran of 11 NHL campaigns as a highly-skilled player, said Gryba's play is as old as the game, that, in essence, it's part of hockey.
That was certainly true when he played, and even as recently 2009, when Mike Richards, then of the Philadelphia Flyers, cranked Florida's David Booth with a blindside hit in the neutral zone.
But it hasn't been part of the game since Boston's Marc Savard suffered a career-ending concussion at the hands of Pittsburgh Penguins forward Matt Cooke.
The NHL ushered in a new rule that forbids hits where the head is both targeted and the principal point of contact.
More pertinently, the league also made it known that the onus is now on the player delivering the hit (although in typical fashion, the NHL gave itself wiggle room in the cases where players recklessly place themselves in vulnerable positions).
Since then, several players have been suspended for hits similar to Gryba's – Edmonton defenceman Andy Sutton (who hit Jeff Skinner of the Carolina Hurricanes), and more recently Montreal's Ryan Whyte, who picked Islander defenceman Kent Huskins' head as he gathered a puck in his own end and turned up ice.
The days when such hits were accepted are over, thanks largely to an improved understanding of the long term effects of concussion.
But the Gryba incident is also rooted deeply in the culture of the game.
Playoff hockey is intense, and predicated on contact. The hit parade started early on Thursday, when Sens behemoth Jared Cowen smoked Montreal's Max Pacioretty (another player who has been on both the giving and receiving end of devastating, illegal hits) in the first period.
Montreal's P.K. Subban replied in kind, blowing up Ottawa enforcer Chris Neil by the side boards.
So when Gryba, a sixth defenceman playing his first playoff game, had the chance to step up on Eller, playing in his eighth, as he took a pass from Raphael Diaz, playing in his first NHL postseason game, he took it.
Doing otherwise would have flown in the face of a lifetime of training.
Eller, it has to be said, was having a stormer of a game, and a defenceman's livelihood depends on slowing such players down.
It's difficult to define intent – a factor that the league has, incorrectly, decided to factor into its disciplinary decisions – but even if Gryba didn't mean to hurt Eller, he certainly meant to hit him hard.
Napoleon famously said no one should presume ill will where simple incompetence suffices as an explanation. But incompetence doesn't excuse responsibility.
Another classic manifestation of hockey culture: the rush to blame the victim (Eller should have had his head up!), and to identify the enabler (Diaz made a suicide pass!), while absolving Gryba (he's not that kind of player, there was no intent to injure).
The aggrieved team offered the usual blandishments about dirty hits, and there's-no-place-in-the-game.
Had it been Subban who popped Ottawa's Jean-Gabriel Pageau in identical circumstances, the sides would have simply switched scripts – it has always been thus.
And there's the crux of the story: the NHL is evolving rapidly, but the players and coaches are convinced it's frozen in amber.