The whirlwind of the NHL offseason has died down and the dog days of summer are starting to set in, which makes it the perfect time to assess and evaluate what has happened since June 15, the night the Chicago Blackhawks won the Stanley Cup at United Center.

With that, here is a list of the 10 teams (listed in alphabetical order) as identified by NHL.com that have improved the most since the end of last season:

BUFFALO SABRES

Key additions: Dan Bylsma (coach), Jack Eichel, Ryan O'Reilly, Robin Lehner, Jamie McGinn, David Legwand

No Eastern Conference team has had a bigger makeover this offseason than the Sabres, who acquired Eichel, O'Reilly, McGinn, Lehner and Legwand on the same day (June 26). The Sabres, who hired Bylsma as coach on May 28, could be in line for the biggest season-to-season win improvement in the NHL. They won 23 games last season; 40 wins this season is a realistic goal provided the goaltending holds up and the Sabres get enough from their defense, which is still in need of improvement. Thirty-five wins might be a more reasonable expectation.

Buffalo's top-three centers are now O'Reilly, Eichel (No. 2 pick in 2015 draft) and Sam Reinhart (No. 2 pick in 2014). The latter are hyped only by potential, but odds are they could be competing for the Calder Trophy with another rookie from Edmonton.

Lehner will finally be given a chance to prove he's a No. 1 goalie. He's 23 and coming off a concussion, but Sabres general manager Tim Murray believes he is a starter and it's hard to find someone who knows him better. Murray scouted and drafted Lehner when he was with the Ottawa Senators.

In addition, Evander Kane should be healthy and ready to make his Sabres debut on opening night (Oct. 8 vs. Ottawa). He was acquired in the blockbuster trade with the Winnipeg Jets on Feb. 11, but had a season-ending shoulder injury at the time.

CALGARY FLAMES

Key additions: Dougie Hamilton, Michael Frolik

The Flames were a surprising success story last season, but it was hard to imagine their success continuing long-term with the way they were winning. They struggled in the possession game (28th in NHL with 44.43 shot-attempts percentage), making them too reliant on third-period comebacks (League-best plus-36 goal differential after the second period), which after a while are unsustainable. Calgary addressed the concerns with the additions of Hamilton and Frolik.

Hamilton is a 22-year-old potential star who was the Boston Bruins' best defenseman last season based on his 54.93 SAT% and 42 points in 72 games. He steps into a defense that was the most productive last season despite not having Mark Giordano, the Norris Trophy favorite at the time he was injured, for the last 21 games.

Frolik was second on the Winnipeg Jets last season with a 55.22 SAT% and sixth with 42 points, including 19 goals, in 82 games. He can play up or down the lineup in any type of role, be it on a scoring line or a checking line. He won the Stanley Cup with the Chicago Blackhawks in 2013.

COLUMBUS BLUE JACKETS

Key additions: Brandon Saad, Gregory Campbell

The Blue Jackets were crushed by injuries last season and still finished with 42 wins. Provided they stay healthy this season, they could be a playoff team, particularly because of the addition of Saad, a two-time Stanley Cup champion with the Blackhawks who is only now entering his prime.

Columbus benefitted from Chicago's inability to come to terms on a contract for Saad because of their salary cap restraints. It's not often 22-year-old two-way forwards with speed and skill become available in a trade. Saad should play left wing on the Blue Jackets' top line with center Ryan Johansen, a combination that should scare every team in the Metropolitan Division.

Campbell is a solid depth signing by general manager Jarmo Kekalainen. He has experience and knows his role as a fourth-line center tasked with taking a lot of faceoffs in the defensive zone. He played it well for several seasons with the Bruins.

DALLAS STARS

Key additions: Patrick Sharp, Antti Niemi, Stephen Johns

The Stars had a strong finish last season, going 14-6 after the 2015 NHL Trade Deadline, but it wasn't enough to make up for their early season struggles. They felt their goaltending depth was a problem, so they addressed it by acquiring Niemi's rights from the San Jose Sharks before signing him to a three-year contract. Niemi will compete with fellow Finn Kari Lehtonen for the No. 1 job. The competition should give the Stars more confidence in their goaltending.

Patrick Sharp brings Stanley Cup championship experience to the Dallas Stars. (Getty Images) Patrick Sharp brings Stanley Cup championship experience to the Dallas Stars.

The addition of Sharp and Johns didn't come cheap. The Stars sent defenseman Trevor Daley and forward Ryan Garbutt to Chicago to get them. Coach Lindy Ruff has options between Tyler Seguin, Jason Spezza, Jamie Benn, Valeri Nichushkin, Ales Hemsky and Sharp. Either way, Dallas' offense, which was already good, is better with Sharp in the mix at the expense of Garbutt.

Johns has a chance to take over for Daley in Dallas' top-six defense group. Defense is still a concern, but Johns comes with potential. He was one of the top defenseman in the American Hockey League last season. He is also 23, so he fits with the young 'D' corps the Stars are building, one that features John Klingberg (22), Jamie Oleksiak (22), Patrik Nemeth (23) and Jyrki Jokipakka (23).

DETROIT RED WINGS

Key additions: Jeff Blashill (coach), Brad Richards, Mike Green

Blashill comes from Mike Babcock's school of coaching, so don't expect too much to change in Detroit. Blashill has been in the organization since Babcock hired him as an assistant coach in 2011. He was the coach of the Grand Rapids Griffins, Detroit's AHL affiliate, for the past three seasons.

Richards is coming off a successful rebound season with the Blackhawks in which he helped them win the Stanley Cup. He will be comfortable as Detroit's second or third center, and will contribute on the power play. Green is the right-handed shooting defenseman in the prime of his career that the Red Wings have been searching for since Brian Rafalski retired four years ago. He also should provide a threat on the power play from the point.

EDMONTON OILERS

Key additions: Peter Chiarelli (general manager), Todd McLellan (coach), Connor McDavid, Cam Talbot, Andrej Sekera, Eric Gryba, Griffin Reinhart, Mark Letestu, Lauri Korpikoski

Similar to the Sabres, no team in the Western Conference has gone through a bigger makeover than the Oilers. Chiarelli was hired on April 24. He hired McLellan on May 19. They've made other significant changes to the coaching and hockey operations staffs with new assistants, new scouts and a new role for former GM Craig MacTavish as Chiarelli's second in command.

The changes to the roster started last month at the draft, when they selected McDavid with the No. 1 pick and acquired Talbot, Reinhart and Gryba in trades.

McDavid is a potential generational superstar who got the NHL buzzing when he scored five goals in a 4-on-4, no hitting scrimmage during Oilers development camp. Talbot will be given the chance to be a No. 1 goalie for the first time in his career after spending two seasons as the backup to Henrik Lundqvist in New York. Reinhart will get his chance to make the Oilers' top-six defense group. Gryba will give the Oilers a physical element on the back end.

Sekera brings instant credibility, and a healthy dose of puck possession, to the Oilers defense group. He instantly became their No. 1 defenseman when he signed on July 1. Letestu and Korpikoski give Edmonton more depth up front.

SAN JOSE SHARKS

Key additions: Peter DeBoer (coach), Paul Martin, Joel Ward, Martin Jones

The Sharks streak of 10 consecutive seasons in the playoffs came to an end last season, so more changes were made to a team that was already in a state of change last offseason. DeBoer replaced McLellan as coach. Martin was signed to a five-year contract. Ward was signed to a three-year contract. Jones was acquired in a trade to replace Niemi, who was traded to the Stars because he wasn't going to be re-signed. The result is a roster that looks like it should be ready to compete for a playoff berth in the Western Conference.

Martin brings more than just experience to the Sharks' blue line. He is a minute-muncher who plays in all situations. DeBoer said he expects to put Martin and Brent Burns together, which should lead Marc-Edouard Vlasic to play with either Brenden Dillon or Justin Braun.

Ward played first-line minutes last season with Alex Ovechkin and Nicklas Backstrom. He has size, strength and skill, making him difficult to match up against. He'll be an important player for the Sharks no matter what line he's on.

It's unclear if the Sharks are better in goal with Jones instead of Niemi, but Jones will be given the opportunity to be a No. 1 for the first time in his career after spending the past two seasons as the backup to Jonathan Quick in Los Angeles.

TAMPA BAY LIGHTNING

Key additions: Erik Condra

Condra is the likely replacement for Brenden Morrow. He's younger than Morrow (28 vs. 36) and can provide more offense in a bottom-six role. Condra had 23 points with the Senators last season; Morrow had eight in 70 games with the Lightning. In addition, Condra should help enhance the Lightning's possession metrics from his bottom-six role. He had a 50.74 SAT% last season, which was slightly better than Ottawa's team percentage of 50.23. Morrow had a 52.47 SAT%, but that was slightly worse than the Lightning's team percentage of 53.03.

TORONTO MAPLE LEAFS

Key additions: Mike Babcock (coach), Shawn Matthias, Daniel Winnik, PA Parenteau, Mark Arcobello, Matt Hunwick, Martin Marincin, Nick Spaling

The Toronto Maple Leafs lured Mike Babcock from Detroit with an eight-year, $50 million contract after. (Toronto Maple Leafs/Light Imaging) The Toronto Maple Leafs lured Mike Babcock from Detroit with an eight-year, $50 million contract after.

The Maple Leafs have made moves this summer intended to make give them a puncher's chance in the short-term with the potential for more assets gained in the long-term, which is all the management group is focused on now. They even sold Babcock on it with the aide of an eight-year, $50 million contract, of course. It's hard to find fault with the way the Maple Leafs are operating their rebuild. It's calculated and it appears Brendan Shanahan and his staff are thinking one or two moves ahead with each decision they make.

Toronto traded Phil Kessel, Tyler Biggs, Tim Erixon and a draft pick to the Pittsburgh Penguins for Spaling, defenseman Scott Harrington, forward Kasperi Kapanen, and two draft picks. It stands to reason that Harrington and Kapanen have futures in Toronto, but Spaling could be trade bait prior to the 2016 NHL Trade Deadline. The same holds true for Matthias, Winnik, Parenteau, Arcobello, Hunwick and Marincin. The Maple Leafs smartly signed all five players to favorable contracts. Winnik is the only player who received a multiyear contract (two years).

They're smart players with strong possession numbers that should be able to help the Maple Leafs stay somewhat competitive, but their favorable contracts allow for the potential, if they're healthy, for them to bring in more assets such as draft picks and prospects, if they are traded.

WASHINGTON CAPITALS

Key additions: Justin Williams, T.J. Oshie

Oshie is expected to slide in on the right side of Nicklas Backstrom and Alex Ovechkin. Oshie, who averaged 56.3 points in the past three full (82 games) seasons with the St. Louis Blues, could see his production spike with the added benefit of playing with Backstrom and Ovechkin.

Williams should be the right wing on the second line with Evgeny Kuznetsov and Andre Burakovsky, unless he loses the job to Marcus Johansson or coach Barry Trotz wants him to remain at center. Williams will provide a steady, veteran presence on that line.

Some definition in the top-six, particularly at right wing on the top line and center on the second line (Kuznetsov) is important because it slots everybody through the rest of the lineup into defined roles. The Capitals still need a No. 3 center, especially if they are going to play Burakovsky on the wing. It's still possible Eric Fehr re-signs to resume that role.

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