Based on the traits they have in common with teams that have gone on unexpectedly deep playoff runs in the past, the Boston Bruins, Calgary Flames and Montreal Canadiens could be this year's dark horses.
Postseason results aren't always predictable, but teams that take the league by surprise usually have some combination of these five elements.
Virtually every playoff contender this season satisfies at least one of those five criteria, but the Bruins, Canadiens, and Flames are the only teams that satisfy at least three, to one extent or another. Let's break down each category to evaluate each team's chances of surprising postseason success this spring.
Hot goaltending
The most common reason that teams go on unexplained hot streaks in either the regular season or the playoffs is that their goalie catches fire.
It might be difficult to predict which goalies are about to get hot, but it is possible to narrow down the possibilities. After all, some goalies have already had hot streaks that are factored into a team's expectations, such as Sergei Bobrovsky of the Blue Jackets and Devan Dubnyk of the Wild. In effect, they will have to get hot just to keep their teams competing at regular-season levels and are unable to boost their squads any higher, no matter how well they play.
Of the remaining teams that haven't already enjoyed hot goaltending this season, those with goalies who have been elite in the past are the ones most likely to be propelled on deep runs. That includes Boston's Tuukka Rask, a former Vezina Trophy winner who is struggling with a career-low .910 save percentage this season, and Calgary's Brian Elliott, who has twice led the league in save percentage but is faring little better than Rask, with a .911 save percentage (though he has been much better as of late, with a .932 save percentage in 19 starts since the All-Star break). Finally, as strong as Montreal's Carey Price has been this season, we know that there's yet another level to his game.
Among the league's other playoff contenders, Henrik Lundqvist of the New York Rangers, Corey Crawford of the Chicago Blackhawks, Braden Holtby of the Washington Capitals and Pekka Rinne of the Nashville Predators could all have a tremendous impact, should they get hot at the right time.
Strong shot-based metrics
The main reason that strong shot-based metrics have indicated playoff success -- instead of other team stats such as special-teams percentage, shooting and save percentages or other goal-based metrics -- is that they tend to be a bit more predictable.
In essence, a team that generates more shot attempts than its opponents in the regular season tends to do the same in the playoffs.
However, the league has been gradually approaching parity in shot-based metrics. The past success of teams with strong shot-based metrics, such as Detroit, Chicago and Los Angeles, along with the growing popularity of hockey analytics in the league's other front offices, has encouraged almost every playoff team to make at least a few strides in this direction.
That means there are only three teams that have averaged at least 52 percent of on-ice shot attempts this season, instead of the usual number (between six and 10).
Boston, which leads all playoff teams with a shot-attempt percentage of 55.3 percent, is the only clear example of a team that could take others by surprise in this regard. Montreal ranks second with 52.2 percent. Although much-improved in this regard, Calgary is not among the league's leaders in this category.
Coaching
When a series is being handicapped, pundits tend to examine every aspect of the matchup except one of the most important: coaching. The experience and prior success of a team's coaching staff have a proven relationship with success in the standings, yet those elements are always overlooked.
Given that a coaching staff's impact will eventually be reflected in a team's performance, the teams most likely to take the league by surprise in the playoffs are those that made more recent changes. Calgary, Boston and Montreal have all had recent coaching changes. Glen Gulutzan took over the reins in Calgary on June 17, Bruce Cassidy took over for the Bruins on Feb. 7, and Montreal hired his predecessor, Claude Julien, one week later.
Several other playoff teams qualify in this category. The Blues and Islanders made midseason coaching changes, Minnesota, Ottawa and Anaheim made coaching changes last summer, and both Columbus and Pittsburgh made midseason changes in 2015-16. That means that the majority of this year's playoff teams will have a coaching staff whose full impact might not yet have been fully realized in the team's performance.
Youth and speed
In last season's playoffs, Pittsburgh's effective use of youth and speed clearly signaled the NHL's new age. But it is not so much that youth and speed are so important; rather, such teams have the greatest potential to surprise.
Because everybody understands the peak abilities of players such as Ryan Getzlaf, Corey Perry and Ryan Kesler, it is commonly known exactly how well Anaheim can perform at its best. In other words, there isn't much potential for a surprise.
On the other hand, nobody knows the maximum upside of Toronto's young players, so there's just no way to predict how well they could play. In a sense, the youth and speed of the Maple Leafs permit them to shock the league in ways that a known commodity such as Anaheim can't.
According to the following table, Calgary and Boston are also among the five teams that have the greatest potential to surprise in this regard:
As of April 1, the Oilers have eight players under 23, followed by Columbus with seven, and there are five teams with six. In Calgary's case, all six players under age 23 were drafted in the first round.
In terms of the combined impact of their younger players, the Oilers lead the way in games played and points, but they are edged by the Maple Leafs in terms of combined goals.
Major lineup changes
One final element that can spark a team is the addition of a game-changing player, whether it's the result of a deadline trade or someone coming back from injury.
In terms of the sheer volume of moves, Montreal and Ottawa each shuffled at least four roster spots, albeit mostly in depth positions. As for Boston and Calgary, their moves were very minor. Boston added Drew Stafford, and Calgary added Curtis Lazar and Michael Stone.
As far as the rest of the league, there aren't any other potential dark horses who have made major changes. Washington made the biggest splash by acquiring Kevin Shattenkirk from the Blues, but the Capitals aren't exactly a team that is off the radar. Likewise, Pittsburgh added defensemen Mark Streit and Ron Hainsey and could be particularly dangerous if the squad starts to approach full health, but the defending champs are already viewed as Stanley Cup favorites.
Final outlook
The Bruins are in a fight for a playoff spot, with a tenuous hold on the second wild card. If they do make the playoffs and are the second wild card (and don't get to third in the Atlantic), the Bruins' first-round matchup is bound to be against the President's Trophy winner, whether that's Washington, Pittsburgh or Columbus. Boston might not be a good dark horse pick after all.
The Flames have all but punched their playoff ticket, and they will likely avoid facing a powerhouse such as Chicago in the first round, but expectations remain low. They have made the playoffs just once in the preceding seven seasons, and in that time, they advanced out of the first round for only the second time since their only Stanley Cup victory in franchise history back in 1989. That makes them a team that could easily take the West by surprise.
Of these three potential dark horses, the highest expectations are placed on the Montreal Canadiens. This is especially true if they win the all-important Atlantic Division title, which would mean avoiding all three Metropolitan division powerhouses until the Eastern Conference finals.
Montreal's history is full of playoff success, but it has been a franchise-record 24 years since the team won the Stanley Cup. This could be the year La Coupe Stanley finally comes home, but it would certainly count as a surprise.