After missing the playoffs in two of the past three seasons — and losing in the first round the one year they did make it — the Bruins are back as one of the NHL’s elite teams.

Entering play Tuesday night, Boston is right in the thick of the Presidents’ Trophy race with Tampa Bay, Nashville and, shockingly, Vegas.

The Bruins won just six of their first 17 games, but are 21-3-4 since, including a 12-0-3 run in their past 15 games. They have not lost a game in regulation since Dec. 14 and are exhibiting all of the traits you expect to see from a Stanley Cup contender.

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Just a couple of years ago, not far removed from their second trip to the Stanley Cup Final in three years, the Bruins looked like an organization that had completely stalled out. Their salary cap situation was ugly and the defense was getting older, going from one of Boston's biggest strengths for so long to its biggest weakness. They clearly needed to do a little retooling, if not an all-out rebuild.

It has not taken them long to retool back into a powerhouse.

It is a fascinating development because of the way this team has been assembled. Specifically, the players that are not a part of it and the sometimes disregard the organization seems to have for elite skill.

When you look at the talent the Bruins have squandered over the years, their success is truly a marvel.

No matter who the general manager has been over the past 15 years (Peter Chiarelli, Don Sweeney … heck, even go back to Mike O’Connell), the Bruins have had a habit of trading the type of high-end talent most teams are desperate to acquire.

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Joe Thornton? Traded.

Blake Wheeler? Traded.

Phil Kessel? Traded.

Tyler Seguin? Traded.

Dougie Hamilton? Traded.

And that list doesn’t even include the good but not quite as dominant players like Milan Lucic and Johnny Boychuk.

Let’s just look at the last four names mentioned: Seguin, Hamilton, Lucic and Boychuk, all of whom were traded within the past four years.

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Today the only player on the Bruins’ roster that was acquired as a result of any of those trades is defenseman Brandon Carlo, selected with one of the draft picks acquired in the Boychuk deal.

The return on the Seguin trade has already completely evaporated — Loui Eriksson left via free agency; Reilly Smith was traded for Jimmy Hayes; Hayes was released; Matt Fraser was lost on waivers; Joe Morrow left as a free agent.

None of the draft picks acquired as part of the Hamilton and Lucic trades (a return that amounted to two first-rounders and a pair of seconds) are currently on the NHL roster. They could still be in the future, and could still be important players at some point, but they are not currently making an impact on a Bruins team that is among the best in hockey.

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It goes beyond that.

Since Seguin and Hamilton were selected with draft picks acquired in the Kessel trade, that means the Bruins currently have nothing to show for one of the biggest blockbusters of the last decade. And since Rich Peverley was acquired for Wheeler (along with Boris Valabik, who later left as a free agent), and Peverley was traded to Dallas as part of the Seguin trade, that means the Bruins currently have nothing to show for Wheeler, either. (It is worth pointing out that Peverley did play a role on that 2011 Stanley Cup winning team … not a huge role, but a role nonetheless).

You would be hard pressed to find an NHL team that has traded that many elite players over a single 15-year stretch for what amounts to so little.

There is a future Hall of Famer in there (Thornton). Wheeler, Kessel and Seguin are all among the best offensive players in hockey right now.

Hamilton is a 20-minute-per-night defenseman who finished in the top 10 in Norris voting a season ago.

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For most teams that trade that level of talent, it probably decimates them and sets them back a decade. Or more.

But during that time period, the Bruins have been to two Stanley Cup Finals, won one of them and since 2007-08 have never finished with fewer than 90 points in a season (the 2012-13 lockout season doesn’t count; they were on a 106-point pace that season and went to the Stanley Cup Final).

That recent trade history should have ruined their chances for consistent, sustained success.

But it hasn’t.

How have the managed to do it?

They still have the best line in hockey

It is a testament to the amount of talent the Bruins have assembled over the years that they could trade that many great players and still have three of the best forwards in the NHL on their roster in Patrice Bergeron, Brad Marchand and David Pastrnak.

They all happen to play together regularly as a trio to form the NHL’s best, most dominant line.

Bergeron has been one of the NHL’s best two-way players for more than a decade, mixing a nearly unmatched combination of shutdown defensive play and high-end offensive talent. He is a 30-goal, 60-point top-line center who can simultaneously render your best player useless and ineffective on any given night.

Marchand can be a loathsome player if he is not on your team, and always seems to be one shift away from doing something stupid that is going to get another call from the Department of Player Safety. Those shenanigans take away from the fact that he has arguably been one of the 10 best players in the NHL over the past three years, scoring at close to a 40-goal pace over 82 games each year while also driving possession and playing great defensive hockey.

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Then there is Pastrnak, the youngest of the trio and perhaps the most gifted offensively. He is still only 21 years old and has already established himself as a 35-goal talent.

When that trio is on the ice together this season during 5-on-5 play, they have outscored their opponents by a 22-3 margin and controlled 60 percent of the total shot attempts.

Since the start of last season, the three have outscored teams by a 48-22 margin when they are on the ice together. When none of them are on the ice? The Bruins have been outscored 128-110. It is a truly dominant, game-changing line when it is together. And on the occasion the Bruins decide to split them up, they can all still contribute on their own.

You need elite players to win, and even after all of those trades over the past decade, the Bruins still have three of the NHL’s best. And they dominate.

Infusion of young talent, underrated draft success

A couple of years ago, the Bruins needed to get younger and cheaper in a lot of areas, and even though there may have been a misstep or two along the way (sometimes a big one), they have found a way to make that happen.

When the Bruins traded Lucic and Hamilton after the 2014-15 season, it helped give them three consecutive picks in the first round (Nos. 13, 14, and 15) and six of the top 52 picks in the draft.

That particular group of first-round picks has become a bit of a punchline after the fact because the player that was selected immediately after was Mathew Barzal. Brazil is having an incredible rookie season for the Islanders and might turn out to be one of the best players taken in that class. The Bruins had three shots at him and missed every time. That doesn’t mean it was a wasted class, and it is already paying off a little for the Bruins.

The second of those three 2015 first-rounders (the pick that originally belonged to the Bruins) was used to select forward Jake DeBrusk.

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Entering play Tuesday, DeBrusk is one of six regulars on the team age 22 or younger and is the fourth-leading goal scorer on the team with 10 goals in 41 games. That is a 20-goal pace over 82 games with almost all of his production coming at even strength.

In the second round, with one of the picks acquired for Boychuk, the Bruins took Carlo, who has become a solid, young NHL defenseman and one of the young players that has helped turn that unit around.

With DeBrusk and Carlo, the Bruins are one of just six teams in the league that has had two players from the 2015 draft class already appear in at least 40 games. They are one of just five teams that already have two players to record at least 20 points in the NHL.

Not taking Barzal is going to hurt, and it’s always going to carry that “what if” along with it, but the Bruins’ stockpiling of picks that year has already given them two regular NHL players and the potential for several more in the future.

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That class came one year after they selected Pastrnak and Danton Heinen in 2014.

The only player selected that year that has more points than Pastrnak at the moment is Leon Draisaitl (the No. 3 overall pick), while Heinen, currently in his rookie season, is also on a 20-goal pace and is tied with DeBrusk for fourth on the team in goals. The Bruins are one of only four teams that have at least two players from that class to already record at least 30 points in the NHL.

They also selected Anders Bjrok (already appeared in 28 games this season with 12 points) in the fifth round.

A year ago, Boston picked Charlie McAvoy in the first round. After giving the rookie his first taste of NHL action in last year's playoffs, they have already bumped him up to a top-pairing defensive role in 2017-18 … as a 20 year old. The only player on the team playing more minutes than him is Zdeno Chara, and he doesn’t look at all out of place.

Boston enigma

In the end, the whole Bruins operation is just … bizarre. I really can’t think of a better word to describe their approach, their moves and the success that comes with it.

They make mind-boggling decisions that should ruin the franchise, but at the same time also find a way to end up doing the right thing.

In one of his last major moves as bruins general manager, Chiarelli bought into the team's own mythology (the whole Big Bad Bruins thing) so much that they actually traded a 21-year-old Seguin for pennies on the dollar, then openly broadcasted the bizarre thought process behind it for everyone to consume. They should have had Bergeron and Seguin, what would have been one of the most devastating one-two punches in the league, down the middle of their lineup for what would have been a total salary cap hit of about $12 million (or the same amount that Edmonton will be paying Connor McDavid starting next season) for several years. It was insane.

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When Sweeney took over behind the GM’s desk, he traded the one defenseman (Hamilton) who should have been the foundation of the blue line for the next decade without getting a single NHL-ready player back in return. He still managed to reconstruct the defense with McAvoy and Carlo as long-term building blocks.

Sweeney somehow turned the last year of Lucic’s contract into what amounted to TWO first-round draft picks (the first-round pick they acquired from the Kings; as well as the first-round pick they acquired for goalie Martin Jones, who was acquired from the Kings for Lucic) and let someone else overpay him. It was brilliant. But they still made huge free-agent investments in Matt Beleskey and David Backes that haven't worked out.

There were 13 teams in 2015 that passed on Barzal … but only one of them (the Bruins) passed on him three times. For about 10 of those teams that passed on him once, it should have ruined that draft, and still might. But the Bruins already have more to show from that class than most teams in the NHL do, with the potential for more in the future.

Never before has a team done so much wrong and still managed to do so much right.