Four of the last five Stanley Cup Finals have featured a team competing in these East Division playoffs. Ahead of the 2021 postseason, each of these four squads has a case to be made as a possible finalist.

The East is also where the fun will get underway, with Game 1 of Capitals versus Bruins kicking off the playoffs Saturday night, followed by Game 1 of Penguins versus Islanders on Sunday afternoon.

1. Penguins (-145) vs. 4. Islanders (+120)

Overall

*five-on-five

Head-to-head

*all strengths

The Penguins last reached the playoffs in 2019 when the Islanders swept them out of the first round. Postseason success has eluded the franchise since it won back-to-back Cups in 2016 and 2017, with Pittsburgh most recently losing to the Canadiens in last year's play-in round. But the Penguins enter these playoffs with renewed optimism after securing their first division title since 2014.

They did so in impressive fashion, navigating the league's deepest division during a treacherous season - one in which they were forced to used 12 defensemen because of injuries, were without Evgeni Malkin for 23 games, and had their GM resign two weeks into the campaign. Pittsburgh had just six players suit up in 48 games or more, the fewest of any playoff squad.

That makes it hard to know exactly what to make of this Penguins team. Pittsburgh's underlying metrics weren't the prettiest, and the team benefited from a high PDO. That typically shouts regression, but is a finally healthy lineup enough to erase those concerns?

Only time will tell, but Pittsburgh should be confident entering this series after finding renewed success against the Islanders. The Penguins have lost to New York just twice in regulation since that sweep in 2019, with their speed giving the Islanders fits and their finishing ability up front emerging as a deciding factor. But the biggest difference has been Mike Sullivan beating Barry Trotz at his own game. Pittsburgh has shown a willingness to adopt a more patient game plan, ditching the eagerness New York punished in 2019.

An upset will require a near-flawless effort from Islanders who - for the second year in a row - saw their season go pear-shaped in the second half of the campaign. They still managed an impressive run to the conference finals last year, but only after a four-month pause that allowed them to hit the reset button. Trotz recently called the postseason itself a reset, but this is a tight timeline for New York to rediscover its form. The Islanders simply haven't looked the same without Anders Lee, and Kyle Palmieri hasn't been able to fill the void.

The Islanders pride themselves on being a strong five-on-five team, but they've posted an underwhelming 48.29 expected goals for percentage since acquiring Palmieri, with Michael Dal Colle and Mathew Barzal the only players sitting above 50%. Trotz continues to throw his lines in the blender in hopes of finding a winning recipe, but nothing seems to be working. The power play remains ineffective - that's been the case for three years now - but it's the impressive five-on-five play that's carried this team in past seasons. If the Islanders can't find success in that area, this series will be over in a hurry.

New York's offense is too reliant on Barzal, and its defensemen don't create enough from the blue line. It leaves the Islanders with a razor-thin margin for success, while the Penguins have an embarrassment of riches up front. We already know the top six will feast - Sidney Crosby and Malkin both averaged at least a point per game against the Islanders this season - but Jeff Carter's arrival has given Pittsburgh a dynamic third line. Carter and Jared McCann each had 11 points in 14 games after the Penguins acquired Carter from the Kings, and linemate Frederick Gaudreau ended the year with six points in as many contests after returning to the lineup. Many hands make light work, and that appears to be Pittsburgh's path to success in these playoffs.

The Islanders' strong suit is goaltending, which can be a great equalizer in the playoffs. New York will lean heavily on Semyon Varlamov - the league leader in goals saved above average - while Tristan Jarry's inconsistencies could open the door for an upset. The Penguins are one bad spell of goaltending away from another first-round exit, but the same can be said of any team. They're also one hot Jarry away from another Stanley Cup, which isn't true of every club.

The Islanders last beat a playoff team on April 6. They're 0-4-2 since then, with just six goals scored. They were a pedestrian 11-13-4 on the road this season - the Penguins were 22-4-2 at home - and lost all four games at PPG Paints Arena. They're limping into the playoffs and - barring a lights-out effort from Varlamov - lack the firepower to give Pittsburgh a real scare in this series.

Pick: Penguins (-145)

2. Capitals (+115) vs. 3. Bruins (-140)

Overall

*five-on-five

Head-to-head

*all strengths

The Capitals and Bruins have combined for 25 postseason appearances and 25 series wins in the past 14 seasons. Yet this will be just their second playoff meeting in that span - and the first since Joel Ward scored the overtime winner for Washington in Game 7 of their 2012 Eastern Conference quarterfinal matchup.

This is the first season since 2014-15 in which the Capitals failed to win their division, and their punishment is a Bruins team that enters the playoffs as hot as any. Boston struggled to find consistency through much of the season's first three months, but a trio of deadline acquisitions has seen this team rediscover its Cup potential and re-establish itself as a top-five club.

Boston added Taylor Hall, Mike Reilly, and Curtis Lazar on April 11, hours after the Bruins suffered an 8-1 loss at the hands of the Capitals. All three have made a significant difference, but none more so than Hall. Boston leads the league with a 63.09 expected goals for percentage at five-on-five with Hall in the lineup - the only team to crack the 60% mark over that span. The Bruins are 12-3-1 in those games, and the second line of Hall, David Krejci, and Craig Smith has been an absolute force. Hall has an expected goals for percentage of 70.1 at five-on-five, with Smith (68.63%) and Krejci (67.45%) not far behind. The trio has also combined for 19 goals and 45 points in 16 games.

That's a nightmare for the rest of the East. The old way to beat the Bruins was to focus defensive efforts on the top line of David Pastrnak, Brad Marchand, and Patrice Bergeron - two 100-point players and the league's best two-way center. It's no longer so straightforward. The emergence of Boston's second line has made the top six a matchup nightmare.

Lazar, meanwhile, has reinvigorated a fourth line that was once a liability. After being significantly out-chanced at five-on-five without him, Boston's bottom forward line has earned nearly 60% of the expected goal share since Lazar's arrival. This is a completely different team than it was before the deadline, so much so that it's arguably wise to ignore everything that happened previously.

What does this mean for the Capitals? Well, it's certainly concerning. Washington is a team that seems to defy logic, always outperforming its otherwise mediocre metrics. But there's clear cause for concern ahead of the postseason. Some of the Capitals' best five-on-five producers are also their worst drivers of play - these issues have just been masked by what feels like an unsustainable finishing rate.

Alex Ovechkin (12%), Nicklas Backstrom (12.4%), and Evgeny Kuznetsov (12.6%) all posted career-best on-ice shooting percentages this season, with all of them finishing well above career averages that hover around 9-10%. As a result, the Capitals finished second in five-on-five shooting percentage on the season, with the Bruins finishing second-last. But Boston and Washington posted nearly identical tallies in that regard over the final 20 games, so regression for both teams - positive, in the Bruins' case - is already underway.

It's just one of a few concerns surrounding the Capitals ahead of this first round. Health and goaltending also remain legitimate question marks. Ovechkin, Backstrom, T.J. Oshie, and John Carlson are all battling through injuries, and it feels like we're not privy to the full picture regarding Kuznetsov.

In goal, which of Vitek Vanecek and Ilya Samsonov can Washington rely upon? The former allowed more than eight goals above expected this season, and the latter close to seven; they ranked 72nd and 66th, respectively, in that regard among all goaltenders. That's a massive drop-off from what Tuukka Rask managed - in a down year, no less - and a legitimate worry against Boston's firepower.

To have success in this series, Washington will likely need to run hot on the power play. That's been this special-teams juggernaut's recipe for success for years now, but it's tough to count on given the standard of officiating in the playoffs. The Capitals also scored nine power-play goals against Boston this year compared to just 4.79 expected, which again speaks to looming regression.

Boston boasts one of the league's best penalty kills, allowing the fewest expected goals against and the fewest high-danger scoring chances against per 60 minutes while shorthanded this season; overall, the team's penalty kill ranked second in efficiency at 86%. As long as they keep Washington's power play from truly catching fire, the Bruins will find their way to the second round for a fourth successive season.

Pick: Bruins (-140)

Alex Moretto is theScore's supervising editor of sports betting. Find him on Twitter @alexjmoretto.

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