(Toni L. Sandys/The Washington Post) (Toni L. Sandys/The Washington Post)

ANALYSIS | The teams in this year’s Stanley Cup finals have been considered among the NHL’s elite for several years. Both the Boston Bruins and Chicago Blackhawks have won a championship in the past three seasons. They aren’t one-hit wonders fueled by a run of luck but teams that have proven staying power atop the league.

Watching the series unfold, it’s hard not to wonder what the Bruins and Blackhawks have that’s missing from the Washington Capitals – one of five teams to make the playoffs each of the past six seasons but the only member of that group not to reach a conference final.

The Bruins at their best are a smothering, punishing team that possesses equal parts skill and snarl. They have offensive talent and the discipline to win one-goal games.

The Blackhawks thrive when their speed and aggressive transition game dictate pace. With scoring threats throughout the lineup, they attack in waves that are usually too difficult to contain.

Each team’s identity is well defined, not only in determining where they want to go but how they intend to get there. For the Capitals, that certainly hasn’t been the case as they’ve cycled through different approaches to pursuing success and were on their third coach in two seasons.

While coaching stability is far from a guarantee of postseason success — see Buffalo and Nashville — it’s no coincidence that Boston and Chicago have long histories with their current coaches despite postseason disappointments and occasional calls for their jobs.

Claude Julien is in his sixth season with the Bruins; in four of those years, they didn’t advance past the second round. Joel Quenneville, in his fourth full season in Chicago, failed to lead the Blackhawks past the second round in each of the previous two seasons. But as depth charts and other factors changed, they’ve both shown an ability to adjust while maintaining the identity they’ve helped build within their teams.

Conversely, Washington’s rapidly changing styles of play and corresponding coaching carousel haven’t done the team any favors.

The Capitals’ first significant alteration came early in the 2010-11 season, during Bruce Boudreau’s final full year as coach. The embarrassing first-round playoff loss to the Montreal Canadiens the previous spring was still fresh when Washington slipped into an eight-game losing streak in early December 2010. Desperate for an end to the funk, the Capitals decided to adopt a more defensive style.

It was a departure from everything they had done under Boudreau to that point, and at times there was hesitancy to their game. In the second round of the 2010-11 postseason, the Capitals folded quickly when Tampa Bay easily counteracted their new defensive measures.

They entered the following season with largely the same approach. After a seven-game winning streak to start the year — during which the team wasn’t playing well so much as managing to eke out victories — the Capitals lost 10 of their next 15 and clearly stopped responding to Boudreau.

In bringing in Dale Hunter to replace Boudreau in November 2011, though, the Capitals made an even more radical shift in ideology. Hunter employed a risk-averse game that valued defense at all costs, handcuffed the players that the team was built around and stripped away remnants of the once potent offensive juggernaut. While the Capitals came within one game of cracking this core’s glass ceiling and reaching the conference finals, they were rarely in control of games — even those they won.

There were lessons to be learned from Hunter, particularly in the self-sacrificial approach to the postseason, but the style was never a long-term solution. At least, not if Washington intended to keep Alex Ovechkin and Nicklas Backstrom as its centerpieces.

In two seasons the Capitals went from electrifying, fire-wagon Presidents’ Trophy winners to trying to rein in that offensive prowess and balance it with a lock-down, trapping defense.

Adam Oates represents Washington’s latest attempt to push the reset button. He believes his task is not only to implement a style of play but to establish a sound identity. Falling between Boudreau and Hunter in the strategic spectrum, Oates promotes offense through a steady defense, and neither lets his star players run free nor restrains them. He laid a foundation in his first season, earning players’ trust and demonstrating how he can help them improve.

But if there’s something to be gleaned from the Bruins and Blackhawks gutting it out in the finals, it’s that excelling in the postseason isn’t a matter of whether players can learn to execute a new system. It’s for a team to truly own how it functions — on the ice and off — and to rely on that foundation when faced with adversity. That takes more than a few months to establish.