When the Los Angeles Kings won Stanley Cups in 2012 and 2014, with a conference final appearance in between, they were known for their “heavy hockey” — a collection of big players who were tough in the corners, slowed the game down, and had enough skill guys on the top units (who were also mostly big guys) to put them over the top.

Guy Boucher was in his second season as head coach of the Tampa Bay Lightning when the Kings won their first Cup. He lasted 31 games in the following season before being fired and ending up in Switzerland, where he coach SC Bern for three years.

The Kings, since winning their second Stanley Cup, have just one win in the Stanley Cup Playoffs, and missed the post-season altogether on two occasions. Boucher returned behind an NHL bench this season with the Ottawa Senators and has led them to becoming the most surprising team of the playoffs, now with a spot in the Eastern Conference Final.

Look around the NHL and you’ll see that the faster teams are now, for the most part, the better teams league-wide. This means not just foot speed from individuals, but being able to quickly move the puck up ice, from defensive zone to neutral zone to offensive zone. No one player in the league is better at doing this himself than Senators defenceman Erik Karlsson, but each of the remaining four teams have some form of speed as a team-defining trait.

“The speed of the game is getting faster and faster,” Boucher said Saturday, when asked how the NHL has changed from the last time he was in the league. “I think what we’re seeing now throughout the league is that your third line now has to be your fourth line. You don’t really have a fourth line anymore. If you have, you can’t make it through. And I think that’s made a big difference.”

As enforcers have gone the way of the dodo, so to has the idea of a plodding, low-minute, grit-and-sandpaper fourth line. In today’s NHL, lines built in such a way are more a liability than anything else.

That doesn’t mean defence has become any less important. On the contrary, Boucher still employs the suffocating 1-3-1 system he did in Tampa Bay. You’ll probably remember the play that went viral when Boucher was with the Lightning, where Philadelphia’s Chris Pronger held the puck in his own end as Tampa’s forwards stood in the neutral zone waiting for the Flyers to move up ice. Pronger refused to move, making a mockery of the conservative style, and forcing the referees to blow the whistle — on Tampa’s home ice no less.

The difference now comes in the kind of players you have up and down your lineup. Depth now really means if you have enough speed to keep up with the other team’s lineup and play through (as best you can) a defensive system designed to slow the game down.

“Our fourth line was like a third line, and you look at every team that’s left, that’s exactly what they’ve got, and that speed on every line is just — the speed now is, I think, the No. 1 thing, even above hockey sense because it’s such a fast league that the fast players will get through your systems,” Boucher said.

Against Pittsburgh, the advantage Ottawa holds is on defence, where they have the best blueliner in the game today and a healthy unit overall. The Penguins, meanwhile, are without star Kris Letang for the rest of the season and minute-muncher Trevor Daley for at least the start of the third round. The Penguins defence is its Achilles heel, and has had trouble in transition and getting itself out of danger when pinned in its own zone. The big star for them on the blue line? Edmonton cast-off Justin Schultz with his eight points in 12 games, but the defenders have mostly been bailed out by Marc-Andre Fleury.

The Penguins still have one of the faster and most skilled lineups in the game of course, with Sidney Crosby, Evgeni Malkin and Phil Kessel up front. Crosby and Malkin are among the top five in playoff scoring while Jake Guentzel is having a huge post-season and Patric Hornqvist continues as a quiet, if key, contributor.

The key for the Pens in the East final, is how they use speed to get through Boucher’s defensive system, even with a hurting blue line corps.

“Whether I use one system or another, in the end, speed right now is the name of the game,” Boucher said. “You see all these young guys that are coming in because of their speed and their stamina and their strength, their explosiveness. They’re ready to play in the NHL quicker and faster, and it’s going to get faster and faster as we move along.

“Four years for me, that’s the biggest change. I think entirely the neutral zone is tougher to get through because everybody’s kind of scared of that speed. It is scary. But did I adjust? A little bit here and there, but not to say that I’ve changed much.”