ST. LOUIS — The team that ranked next to last in scoring this season, the same players who generated four goals in a game only twice in a dark December that began and ended with different coaches behind their bench, shredded the NHL’s best defensive team Monday and drove the league’s stingiest goaltender to slam his stick against the post in frustration.

Brian Elliott’s swing produced the most solid contact he made all night. He certainly didn’t make contact with enough of the Kings’ 21 shots, though his overmatched defense didn’t help him much in a game that disintegrated into a series of scrums and clinches.

The Kings, a prime culprit in the league’s scoring decline this season, scored four goals in one period of a playoff game for the first time since 1993 — and they didn’t stop there. With a 5-2 victory over the St. Louis Bluesat Scottrade Center, they took a 2-0 lead in this second-round playoff series and stretched their postseason road winning streak this spring to five, seizing command of a series that shifts to Staples Center for games on Thursday and Sunday.

PHOTOS: Kings vs. Blues, Game 2

Where was this potent, forceful team most of the season, when they had to scrape for goals and Jonathan Quick’s sustained excellence in goal was all that kept them competitive?

“I don’t know,” Dustin Brown said. “I’m fine with it showing up right now.”

Brown is a key reason the Kings are, by their standards, filling the net. They averaged 2.29 goals per game during the season but are averaging 2.86 in the playoffs (20 in seven games) to rank fourth among playoff teams. Brown has played a role in all four of their short-handed goals, including knocking the puck down and passing it to Anze Kopitar for the first-period goal Monday that seemed to stun the Blues into passivity, and his three-assist game on Monday gave him nine points.

Kopitar, who also scored late in the first period to give the Kings a 4-0 lead, has three goals and six points. And as proof that wonders never cease, the seemingly unmotivatable Dustin Penner has played with passion and the skill everyone knew he had but few could excavate.

He set up Mike Richards’ goal 31 seconds into the game and the Jeff Carter goal that gave the Kings a 3-0 lead.

His teammates repaid the favor after he was leveled by Blues forward T.J. Oshie in the third period, with Richards getting into a tussle to retaliate for the hit.

“I’m a big fan of him,” Penner said of Richards, whom he later sent a tweet of thanks on his new Twitter account (@dustinpenner25).

“I think he’s got a lot of fans, just the way he plays the game. He’s a great two-way centerman. He arrives to every part of the ice with ill humor. He doesn’t give anybody an inch no matter who they are out there and he’s been able to be a calm, quiet steady leader on this team with his play on the ice.”

Asked when Richards had become that kind of player, Penner said Richards always had been. “You only notice it now because there’s eight teams left,” Penner said.

And the Kings are one of those eight, halfway to becoming one of the final four, a destination they’ve reached only in their 1993 Stanley Cup run.

Coach Darryl Sutter had no interest in discussing whether he had envisioned this when he succeeded Terry Murray in mid-December. “I know there’s a lot of good players on our team. It’s hard getting them all to play together at the same time,” he said. “I just look at it as a series. I don’t really look at it as an overview.”

Here’s an overview: The team that couldn’t score suddenly can’t lose. Like Brown, Kopitar said he didn’t know where this team was most of the season.

“If I knew we’d probably break out before and probably wouldn’t have made it as tough on ourselves as we did, clinching the playoffs the last week of the season,” he said.

“But that doesn’t matter right now. We’re in obviously a pretty good position right now, halfway there, but there’s lots of work left to be done.”

And, apparently, a lot of goals to be scored.

helene.elliott@latimes.com

twitter.com/helenenothelen