BOSTON -- The Boston Bruins are undefeated and unblemished through their first three games of the season, a perfect 3-0-0. 

Deeper than the perfect record, the Bruins also tote a perfect penalty kill, having sufficiently killed 12 of 12 kills, all in games that amounted to one-goal affairs with Boston adding empty netters in their two regulation wins.

In Boston's first game, a road trip to face the Washington Capitals, the Bruins killed off five Alex Ovechkin-led power plays, leading to an eventual 3-1 road win (with an empty netter).

The very next day, Boston held Connor Bedard's plucky Chicago Blackhawks three power plays silent, leading to an overtime victory.

Then last night, while Tage Thompson and the Buffalo Sabres surged hard, Boston held them off the board, killing all four penalties en route to another 3-1 victory (with an empty netter).

Three games, all decided by one goal, all featuring heavy doses of Boston's kill. Sean Kuraly, Tanner Jeannot, Fraser Minten, and Mikey Eyssimont have all featured on the kill to great success, and none of them were on the Bruins last year. 

It's an early feather in the cap of Bruins General Manager Don Sweeney, who set out to build a team that's very hard to play against. So far, that's exactly what Boston's been, led by the penalty kill.

But what specifically has made the kill just so effective, even in these early days?

Bruins Head Coach Marco Sturm has the unit playing an aggressive, in-your-face style that's flummoxed and suppressed every opponent they've faced thus far.

"We want to be aggressive," said Sturm on Saturday night following the 3-1 victory over the Buffalo Sabres. "But also, I think we feel comfortable now doing it. When you play that kind of system, it usually takes a while at the start, [players think] 'Should I go, should I not?' 

So there is a little bit of a trust issue, which is normal, but now they don't even think. They just go, and they know exactly what to do. We all land on the same page, and yeah, for example, on the kill, your goalie also has to be your best killer. Sway again, tonight he was outstanding."

Boston's hard work was plainly evident last night. Minten and Jeannot led multiple shorthanded odd-man rushes, but couldn't buy a goal. Mark Kastelic, who might've been Boston's best skater on the ice last night, generated a chance by intercepting a pass and nearly scoring on a partial break.

"I think just everybody's on the same page," said Kastelic of the penalty kill. "One and two, we're just on our toes, and we're aggressive. Nobody's sitting back; everybody's competing, and everybody's taking a lot of pride in that on the PK. Which, I think, is the biggest thing. So, that's what I'd probably go with."

"I think just everyone being on the same page,"  said Jeannot. "Knowing your reads, knowing your job, and your assignments. It's playing hard, winning every battle, and face-offs are a big thing. Guys are digging in right now, and it's awesome."

It's been a shared theme—one of direct, intentional intensity. Nobody has a better view of that up close than Jeremy Swayman, who Sturm deemed Boston's best killer.

What Swayman sees is pure hunger and drive out of his teammates.

"I think their intensity," said Jeremy Swayman, when asked why the kill has been perfect to start the season. "It's our four outwork their five, and it's obvious. That's something that we all can get behind and stick to within our identity. I know it's just a huge momentum shift for us when we get kills like that.

I'm just so happy with the guy's effort and attention to detail, sticks and lanes, and obviously blocking shots and good communication."

It's hard to receive praise any higher. Swayman's answer boils down to Boston quite simply wanting it more and proving it with their work. It'd be impossible to argue against Swayman's assessment of the situation, based on results and chance generation.

As mentioned before, Sweeney's summer additions have all looked like winners through the first three games. But that message of toughness and season goal runs deeper. Sturm looks to be a home-run hire. Most importantly, he's rebuilt the Boston identity and culture in no time at all.  

"You can see it in the game today," Sturm said after Saturday's win against Buffalo. "Everyone is excited to play. Everyone works. We’re a family. That’s what family does: Support each other. We help each other. That was our message."

That connectivity and energy have powered Boston through the very early days of this season. It's something that Bruins President Cam Neely hoped to see when he talked about the Bruins' roster in his beginning-of-season press conference, a renewed culture. He and Sweeney bet that it would come through one identity, committed to tough defense and winning.

"We're going to have to play tight defense if we want to be one of the eight [playoff] teams," said Neely. "We got guys who are going to be tough to play against, hard to play against.

"I think teams are going to circle playing against the Bruins and go, ‘Oh damn, we have to play them tonight.’ That is the type of lineup we put together."

One week later, Neely's words have rung prophetic. The Bruins are an impossibly tough matchup, with their stinginess leading the way. 

Tomorrow afternoon brings the always-prolific Tampa Bay Lightning, one of the best offensive teams in the league, perennially toting a lethal man advantage.

It'll be Boston's biggest test to date before they head out west for a three-game trip.