Matt Duchene preferred to bite his tongue on the topic of penalties and fewer whistles these days. His stitched-up lip spoke loudly, though, courtesy of a recent cross-check that didn’t result in a call or a power play.

“I have to be careful what I say here,” the Colorado Avalanche forward said. “But I’m very opinionated on it. … I don’t know whether the standard has changed or not.”

League-wide, penalties have dramatically dipped from a decade ago. In 2005-06, there was an average of 11.7 power-play opportunities per game for both teams, according to STATS. Last season, it hovered at 6.1 and so far this year, the number is 6.3.

Less fighting is a reason, obviously. But so is this: Players have simply adjusted to the way officials call holding, hooking, slashing and other penalties. Consider this: The average margin of victory this season is 2.05, the third-lowest average in league history (figures don’t include games that went to a shootout or used to end in ties). It’s been a long time since games have been this close — 1.92 in 1928-29 and 2.02 in ’35-36.

So, yeah, careless penalties matter.

“Players are real smart, especially hockey-wise, that if you continue to get called for hooking, holding and interference, after a while you don’t play,” said Stephen Walkom, NHL director of officiating. “So you’re seeing the results of that — the players fearing the officials are going to call it and the coaches telling players they can’t take penalties because it will hurt them as a team. There’s a ton of conformance, which is great.”

The lack of power plays very well could be another reason scoring is down, from 6.05 goals per game in ’05-06 to 5.25 so far this season. It’s the lowest total over the last decade, according to STATS.

“It’s kind of a double-edged sword, because you want to be able to score more,” New Jersey coach John Hynes said. “But I think from the players’ perspective, too, when you get into those special teams games, a lot of times it disrupts the flow. Sometimes it’s nice, because you have scoring opportunities. But even for the fans, it’s not as uptempo or competitive at times.”

No surprise, roughing and fighting calls are down this season. So are elbowing, boarding and hitting-from-behind infractions from a year ago.

“The game is way safer, way more skilled and players conforming to the rules — or at least know where the line is like never before,” Walkom said.

However, tripping calls are on the rise in ’15-16 in part because players are trying to keep their sticks closer to the ice to avoid hooking penalties — an interesting penalty and more difficult to discern.

“What a hook was 11 years, three tugs, my grandmother could make those calls,” Walkom said. “I don’t mean any disrespect to my grandmother, but if I showed her a video, she’d be like, ‘That’s not fair.’ But in today’s game, where there’s a hook on the hands — happens really fast and takes away the shot — it’s as important as the big tug was 11 years ago. But those are even harder to see.”

Same goes with a slash. New York Islanders forward John Tavares has received his share of stick taps to the gloves as he flies into the zone.

“You can’t hook guys, you can’t grab guys, but a lot more small little chops, just on the hands,” Tavares said. “It affects players making plays. I’ve noticed that and it doesn’t get called quite as much, because they’re looking for the clutching and grabbing. It’s just players getting much better with the rules and at the same time making adjustments, finding ways they can be effective and disrupt players without taking penalties.”

As for players grousing over calls, well, that’s just part of the game.

“That’s the beauty of hockey, too, that any good player can be a great politician because they’re lobbying all night,” Walkom said. “Players know every inch (of ice) matters out there and every call matters. I don’t blame them. The game today isn’t like 10 years ago. And 10 years from now, it will be a different game, too.”