Penalty killing is an essential part of being a successful NHL team, and it’s one weakness the Boston Bruins must fix as soon as possible if they’re to return to the Stanley Cup playoffs this season.

The B’s have given up a power-play goal in 12 of 14 games played, including three games of multiple PPGs allowed. As a result, Boston ranks 30th in the NHL with a 70.4 penalty kill percentage, and its 16 power-play goals against are the most in the league.

“We work on (the penalty kill) a lot and we do a lot of video and stuff,” Bruins forward Brad Marchand told reporters after the Dallas Stars scored three PPGs in a 5-3 win over Boston last week. “We don’t seem to be cutting those lanes the way that we used to, and we haven’t had as good of sticks, and I think we really have to focus on getting the puck down on the opportunity.

“We haven’t necessarily done that and we’ve been playing against some pretty good power plays, and you know it’s enough to win or lose games when the PK doesn’t step up, so we have to do a much better job.”

Penalty killing has been one of the Bruins’ strengths throughout Claude Julien’s tenure as head coach, but some issues on the current unit prevent it from being consistently successful.

One of them is goaltending.

Starting netminder Tuukka Rask hasn’t played as well as expected this season, although he isn’t even one of the top three or four problems for this team. That said, Rask has a league-worst .702 save percentage on the penalty kill, and his .729 adjusted save percentage on the penalty kill is the second-lowest among all goalies.

In Rask’s defense, he typically has received little help from the players in front of him. The Bruins too often are giving up too much time and space to opponents on the penalty kill.

On one of Tyler Seguin’s goals from last week, the Bruins allowed the Stars forward a lot of time and space with the puck and didn’t get into the shooting lane, which might have blocked his shot or forced him to pass. Instead, Seguin rips a shot that beats Rask far side, with a big power forward in Jamie Benn setting a screen.

Screen Shot 2015-11-11 at 12.37.23 PM

In the second game of the season, against the Montreal Canadiens, the Bruins gave up the first goal when David Desharnais scored in front of Rask after the goalie made a tremendous save on a cross-crease pass. Desharnais was able to whack at the puck several times before scoring, and no B’s defensemen cleared him or the puck from that area.

The Bruins have been able to survive to some degree without a good penalty kill because their power play has had the opposite effect, with a league-leading 33.3 percent success rate. That kind of rate likely will regress, though, since the Washington Capitals and Detroit Red Wings are the only teams since the 2004-05 lockout to finish a season with a 25 percent conversion rate on the man advantage.

When the offense cools off or goes through droughts, the penalty kill will need to step up. Fifteen of last season’s 16 playoff teams ranked inside the top 20 in penalty killing, and eight of the clubs in the top 10, including both Stanley Cup finalists, also earned a postseason berth.

Therefore, the Bruins must improve their penalty killing to make the playoffs out of a competitive Atlantic Division, where spots two through seven were separated by just three points entering Wednesday’s play.

Thumbnail photo via Geoff Burke/USA TODAY Sports Images

Thumbnail photo via Nov 5, 2015; Washington, DC, USA; Washington Capitals left wing Alex Ovechkin (8) scores a goal on Boston Bruins goalie Tuukka Rask (40) in the first period at Verizon Center. Mandatory Credit: Geoff Burke-USA TODAY Sports