When the Boston Bruins made the Stanley Cup Playoffs 15 times in an 17-year span from 2007-08 through 2023-24, the foundation of their success was being a strong defensive team.

Sure, having elite goaltending during much of that span helped a lot. But the Bruins were really tough to play against, and opponents had to earn every Grade A scoring chance. The B’s allowed the fewest goals and ranked No. 1 in penalty kill percentage over that 17-year run.

That level of defensive dominance is no longer seen on Causeway Street.

The Bruins have been one of the NHL’s 10-worst defensive teams this season. Couple that with some lackluster goaltending of late and you have a recipe for disaster.

A little less than a month ago, the Bruins were tied for first place in the Atlantic Division. They are now in seventh place and three points out of a playoff spot after losing seven of their last nine games.

The most recent matchup was a 7-4 defeat to the Seattle Kraken on the road Tuesday night. It was the 16th time that Boston has allowed four or more goals in a game this season, and we’re barely past the halfway mark.

The Bruins rank 25th in the league in shot attempts allowed at even strength. They have given up the sixth-most high-danger scoring chances during even-strength action.

The B’s rank 31st in expected goals against but 16th in actual goals against at even strength, which is a testament to how well the goaltending has been at certain points in the season. For example, without Jeremy Swayman posting a .935 in 10 November appearances, the B’s would be in far worse shape.

The Bruins are not making life easy for Swayman. Only one goalie — Juuse Saros of the Predators — has faced more high-danger shots against than Swayman’s 251.

It is unrealistic to expect your goalies to bail out the team’s defensive miscues for a large chunk of the season. The defense in front of them has to improve.

This goal from Tuesday night cannot happen. Berkly Catton gains the blue line, passes to his right and then skates to the front of the net completely unopposed and scores. He skates past three B’s players and faces no resistance.

When the Bruins give up cheap goals and fall behind, they create a pretty difficult challenge for themselves. They are not built to play from a deficit, evidenced by their 0-16-0 record this season when trailing after two periods.

Another major issue for the Bruins is discipline.

This team spends way too much time in the penalty box. The B’s have taken 187 minor penalties, which is 11 more than any other team. They’ve been shorthanded a league-high 167 times, which is at least 22 more than any other team. Therefore, it’s not surprising that their 35 power-play goals against are tied for the league lead. In Tuesday’s loss, the Bruins gave the Kraken four power plays and Seattle scored on three of them.

Spending so much time on the penalty kill is a tough setback for a Bruins team whose roster is less talented than many of its opponents.

The Bruins have to defend better as a team and individually to give themselves a chance at making a real playoff push in what has been a very competitive Eastern Conference so far this season.

The good news for the Bruins is, because the standings in the East are so jam-packed, their lack of wins lately has not sunk them into an unrecoverable hole. There is still time to fix things and re-establish the defensive identity that made the Bruins so hard to play against for many years.