It’s no secret.

We knew coming into the 2015-16 NHL season that the Boston Bruins’ defense was the team’s Achilles heel- the one area of contention that could sink the club’s hopes for an improved season after barely missing the playoffs a year ago.

They’re a game but ultimately mediocre bunch who have been exposed at the campaign’s most crucial juncture and even the fighting spirit that the 2015-16 Bruins have exhibited for much of the year isn’t enough to hide the warts with this group. It didn’t happen overnight, but the inexorable slide of the once-vaunted Boston D Party that won a championship in 2011 and got the Bruins close again in 2013 began in earnest with Dennis Seidenberg’s catastrophic knee injury shortly after he inked a 4-year, $16 million extension during the 2013-14 season.

It continued with a cap-constrained team that was forced to make fateful decisions that ultimately put the defense in the situation it is in now.

In 2014-15, a disastrous campaign that saw a team with significantly higher expectations begin the dismantling of a serviceable if not spectacular defense corps on the eve of the season when GM Peter Chiarelli traded fan favorite and dependable, versatile and heavy D Johnny Boychuk. It doesn’t matter as much to the fans that the move was to help get the team cap compliant, because in hindsight, there were other players who could have been cut loose to make the dollars work and not have the detrimental impact Boychuk’s change of address to the NY Islanders created for the B’s. It was a move that ultimately helped lead to the end of Chiarelli’s tenure in Boston at the conclusion of Boston’s first missed playoff season since 2007. Even so, you could make the case last season that the defense was less responsible for the Bruins’ inability to make it into the postseason (the offense went cold during a six-game losing streak (three of those losses came in OT so they got 3 points of 12) in March and then mustered just four goals in the final three regular season games, going 0-3), the blue line is the major culprit for the deja vu that the team finds itself in one year later.

In 2016, it isn’t as difficult to diagnose what ails this team most. Yet, it seems inconceivable that after a year of ups and downs, but few extended lows because of a spirit the current Bruins possess, that it’s all on the verge of unraveling altogether.

Three weeks ago, the B’s were sitting second overall in the Eastern Conference as they embarked on a California road trip that would begin a similar disastrous five-game swoon, all happening in regulation, a losing streak that might have cost them the playoffs for the second season in a row.

The B’s now face another do-or-die three-game stretch to close out the year: they died a year ago, dropping the trio of games when the offense deserted them.

This time, the team will attempt to stop the bleeding on the back end and even though the situation is hardly all Tuukka Rask’s fault, neither is it taboo to point out that he could elevate his play during this crucial stretch of games. It is not a zero-sum option here- it’s OK to say that Rask could be better than he has shown in recent contests without bringing out a legion of sycophants that doesn’t ever seem to want to hold Boston’s 7 million dollar goalie accountable for anything. It’s almost as if no goal allowed is ever on the one player who in many instances has the power to make a stop, even when the team in front of him “hangs him out to dry.” It’s a curious development- I’ve honestly never in my life seen such a willing group who will defend a player to the death while pointing the finger at everyone else but their guy.

The fact is- the entire team is to blame for the situation. The goalies. The forwards. The coaches. Management. Most certainly the defensemen. Everyone.

But blame is such an ethereal thing. Once you’ve pointed out the obvious or vented your impotent rage against your television or computer screen (or both) where are you? Blame is a part of life especially when it comes to fandom and sports, but simply blaming the Bruins for the current state of affairs falls short of the mark for what should be a substantive debate over what can and should be done going forward.

It’s too easy to simply point to the current state of affairs on the blue line and expect that Don Sweeney should have built Rome in a day last summer by fixing all of the myriad issues surrounding the team. Of course, trading Reilly Smith for a young, potential solution to the ills of this defense might have been preferable to the return the team has gotten from Jimmy Hayes, the reality is that at the time, the Hayes acquisition was well-received. Coming off a career- best 19 goals, it was a reasonable expectation that he might get 25 this season playing for his hometown team. Didn’t happen, and now Sweeney must figure out what to do with Hayes. The easy answer is to move him, but the tougher challenge is that Boston is selling low on the former 2008 second-round pick.

Regardless of what happens in the next three games, all paths lead to a significant shakeup on defense this coming offseason. Sweeney now has a year under his belt calling the shots and he showed last June he wasn’t afraid to make some bold decisions. Criticizing him for not going out and getting more help on defense is the lazy, hindsight being 20/20 argument, even if it might be true. What we don’t know is what options he had beyond a mediocre free agent group (does anyone think Buffalo got their money’s worth with Cody Franson?) and what he tried to accomplish after making the tough call to move Dougie Hamilton for three assets but not one of whom had a prayer of helping the Bruins *this* season?

Now, some contracts coming off the books and other extensions to (likely) be signed, Sweeney does have a little room to maneuver for an NHL roster defenseman. Whether it’s Kevin Shattenkirk or one of the myriad other names that have been floated out there, something’s gotta give. He’s got some organizational assets in the form of roster players, prospects and draft picks to use as currency to get a defenseman or two, but that has to be the focus. You just hope that whatever the GM is able to do, he won’t rob Peter to pay Paul.

What we do know and have for sometime now is that despite a gritty, gutsy effort to climb near the top of the Eastern Conference standings (at least as close to the President’s Trophy-winning Washington Capitals as realistically possible), the defense came back to haunt the team as a whole, and to be completely honest- the offense and goaltending had their part to play in Boston’s current situation, which has them out of the playoff architecture after getting shellacked for 6 goals in nearly two periods in Chicago before scoring four unanswered goals in the game’s final 21 minute to make it less of a fiasco than it actually was.

Again- no one is blaming Rask for all of Boston failures, but the team needs him to play his best hockey of the season over this next trio of games or it is over…o-v-a-h. Literally. The cynics, many of whom wasted no time sharpening their knives in recent weeks and especially after the Sunday loss to the Blackhawks, will say it already is fait accompli that Boston misses the playoffs. Maybe, maybe not. I do know that not making the dance and getting the 14th overall pick in a top-10 group for the second consecutive year is worse than kissing your sister.

At least we have new lottery rules that give the 14th and final non-playoff chances at least some odds (no matter how miniscule) at land the 1st, 2nd or 3rd overall pick. Absent that, selecting 14th is little consolation for another so close, but so far away finish. Picking 14th year after year makes it even tougher to get those critical difference-making players that earlier selections will net rebuilding teams. Success is not a given,  just ask the Edmonton Oilers. Middle-of-the-pack drafting makes it that much harder to build a champion from the ground up, though.

As for the defense, it’s not all their fault either. Zdeno Chara is aging rapidly and I’m still convinced that his right knee injury from a year ago is still and will continue to hamper his play going forward. Torey Krug is a top-4 NHL defenseman, but is he closer to four than two and more impactful on special teams? He deserves a raise and should be kept and a part of an improved group going forward even if his goal numbers have suffered this season. Adam McQuaid’s a good guy but he doesn’t carry a great cap hit for what he brings, especially when he’s asked to play a larger role than the one to which he’s best suited. John-Michael Liles provided a nice late-season boost, but he’s not the kind of true difference-maker and two-way stalwart for the long haul the B’s need.

The losses of Seidenberg and Kevan Miller to injury have exposed the B’s who are affected without their experience and heavy game. Joe Morrow demonstrated that with a desperate and ill-advised cross blue line pass that Patrick Kane picked off and broke the game open with in the first of his Sunday hat trick. Nobody’s saying that Seidenberg and Miller are the core of a championship-caliber group, but perhaps those pining away for skilled but neophyte defenders with questionable defensive acumen like Morrow and Colin Miller (recalled today, btw) were reminded of why rolling the younger D out for big minutes this season didn’t happen.

The Bruins have a shot. They play three winnable games this week at home. At home! What could be better than a three-game TD Garden stand to close it all out? Amirite? Oh, wait a second…

To close it out, Sweeney knows what kinds of steps he needs to take, but it’s much easier said than done.

He made his mark with some bold moves in his first days as Bruins GM. He’ll have to tap the well of audacity once more. But, it’s more than just making roster changes that will likely be dissected every which way from Sunday when they occur. Along with a willingness to make major sea changes, the former NHL defenseman who played more than 1,000 NHL and most of them in the spoked B of the team he now presides over, will have to prove himself all over again.  If he can identify some key pieces at that very position and if he not only succeeds in acquiring them, but gets the kind of production out of them that can help get the Bruins back into contention, he’ll buy some measure of reprieve.

But the margin of error is shrinking. The nature of Titletown USA- that is- nine professional sports championships in Boston since 2002 between the Patriots (4), Red Sox (3), Celtics and Bruins, means that the natives have come to expect success.

Patience is not a virtue.