Ranking the 10 Biggest Roster Moves from the 2015 NHL Offseason so Far

This summer has been exciting for fans as blockbuster trades replaced the free-agent frenzy. The storm was inspired by cap-crunched teams and especially the Boston Bruins—who changed their look in one incredible day.

Aggressive teams broke through with major additions, and that means clubs that were not active may have lost significant ground by standing still. The changing of the guard in each division of the NHL may be substantial based on the work done by general managers this summer.

Here are the 10 franchise-altering moves of the 2015 offseason.

10. Detroit Red Wings Sign Mike Green

Geoff Burke-USA TODAY Sports

What's The Deal? The Detroit Red Wings don't have a history of spending big money on free agents, but Mike Green is a unique player. His specific talents—including a great point shot—made him a worthwhile investment. 

What Is The Immediate Impact? Green is a veteran defender who can step right in to a seasoned group of rearguards in Detroit. He can play up and down the depth chart as needed and will add to the Red Wings' arsenal with the man advantage.

How Much Does it Improve the Team for 2015-16? Detroit's defense is a veteran crew, and Green will be a part of an established group. His impact will come mostly on the power play, but as a veteran the defensive side of his game will be important as well. The Red Wings are unlikely to put him in a position where he's facing the toughest opposition in the game.

9. Washington Capitals Sign Justin Williams

Adam Hunger-USA TODAY Sports

What's The Deal? The Washington Capitals made the best value signing in free agency by getting winger Justin Williams at $3.25 million per season on a two-year deal. 

What Is The Immediate Impact? The Capitals have a responsible two-way winger who can play up and down the lineup as required. It's a major deal, as Washington had some chemistry issues for its top line during the year.

How Much Does it Improve the Team for 2015-16? Washington is likely to use Williams on a line with skill, because he can help offensively while also doing the checking chores. Last year, Nicklas Backstrom and Alexander Ovechkin played a lot together, but the third member of that line was a moving target. From Tom Wilson to Jay Beagle, nothing seemed to fit. Justin Williams plays effectively with Jarret Stoll and Marian Gaborik, giving him added value to any team.

8. Anaheim Ducks Trade for Carl Hagelin

Kathy Willens/Associated Press

What's The Deal? The Anaheim Ducks upgraded in experience when they acquired Carl Hagelin from the New York Rangers. The package—which included several pieces both ways—centered around Hagelin and speedster Emerson Etem. The Rangers dealt Hagelin at least partly due to cap worries. 

What Is The Immediate Impact? The Ducks have an established winger to add to a strong group of forwards. Hagelin is fast, can play either wing and is reliable in all aspects of the game. A young veteran of his calibre doesn't come available every summer.

How Much Does it Improve the Team for 2015-16? Hagelin is a plug-and-play forward who can buzz saw the opposition with his speed and skill. Anaheim is close to being a Stanley Cup team, and this addition—for what amounts to picks and prospects—was a nice add.

7. Edmonton Oilers Select Connor McDavid No. 1 Overall

Alan Diaz/Associated Press

What's The Deal? The Edmonton Oilers won the draft lottery in a year it really mattered and their prize was Connor McDavid. He is the best draft pick since Sidney Crosby a decade ago and is regarded as a franchise cornerstone.

What Is The Immediate Impact? The acquisition of McDavid via the draft gives the team immediate credibility—something that's been missing since the spring of 2006 when Edmonton made it all the way to the finals. The Oilers have missed the playoffs every season since 2006-07, and the franchise has never had a Calder Trophy winner for the rookie of the year.

How Much Does it Improve the Team for 2015-16? McDavid's junior numbers are phenomenal, and it's likely he'll post a good number as an NHL rookie. If he ends up with linemates like Taylor Hall and Jordan Eberle, it's possible he scores 70 points next year. If those two wingers find themselves with Ryan Nugent-Hopkins at center, McDavid will face softer opposition with wingers like Benoit Pouliot and Teddy Purcell. A point total of more than 60 is likely in any case, giving Edmonton their best elite young talent. 

6. Dallas Stars Acquire Patrick Sharp

John Raoux/Associated Press

What's The Deal? The Dallas Stars made a significant deal with the Chicago Blackhawks on July 10. Dallas sent defenseman Trevor Daley and forward Ryan Garbutt to the 'Hawks for veteran forward Patrick Sharp and prospect defender Stephen Johns. 

What Is The Immediate Impact? The Stars are a formidable offensive team but lack quality two-way forwards to make sure the defensive end is secure. Sharp can be placed on any offensive line with confidence, as he can play a complementary offensive role while also providing the checking conscience for a line. 

How Much Does it Improve the Team for 2015-16? Scoring is no problem for Dallas. It has impact forwards in Jamie Benn, Tyler Seguin and Jason Spezza. What it's lacked in recent seasons is a versatile two-way forward who can play with those skilled men while also offering cover when possession changes hands. Adding Sharp to the gifted group in Dallas is a home run addition. 

5. Columbus Blue Jackets Land Brandon Saad

Paul Vernon/Associated Press

What's The Deal? The Columbus Blue Jackets pulled off a huge trade with the Chicago Blackhawks on June 30. Brandon Saad has a new home with the Blue Jackets and a package went the other way, including Artem Anisimov and top prospect Marko Dano. 

What Is The Immediate Impact? The Blue Jackets immediately improve their scoring depth. Last season, four forwards—Nick Foligno, Scott Hartnell, Ryan Johansen and Cam Atkinson—scored 22 or more goals. Saad scored 23 and is at an age (22) where he could explode as an offensive player.

How Much Does it Improve the Team for 2015-16? Columbus had issues with secondary scoring a year ago, and this move addresses the problem in a big way. Ryan Johansen had success with many wingers a year ago, and Brandon Dubinsky performed well when healthy with Matt Calvert and Cam Atkinson. The addition of Saad gives the Blue Jackets an upgrade for their two scoring lines, and the team now has enough skill left for a significant upgrade to the bottom six forwards. 

4. Buffalo Sabres Add Ryan O'Reilly in Blockbuster Trade

Jack Dempsey/Associated Press

What's The Deal? The Buffalo Sabres changed the course of their team history on June 26. The team drafted Jack Eichel No. 2 overall and then proceeded to make a massive trade on the draft floor. The Sabres acquired impact two-way forward Ryan O'Reilly from the Colorado Avalanche for a package of picks and players. 

What Is The Immediate Impact? O'Reilly is a major step up over any forward on the Sabres roster. He's a complete player, able to help in all areas and impact on the power play at even strength and penalty kill.

How Much Does it Improve the Team for 2015-16? O'Reilly is a veteran center who can flourish against tough opposition—one of the rarest feats in the game. He can provide cover for rookies Eichel and Sam Reinhart and play in the most important moments of the game. Buffalo hasn't had a center like O'Reilly in years.

3. Calgary Flames Acquire Dougie Hamilton

Michael Dwyer/Associated Press

What's The Deal? The Calgary Flames made a stunning deal with the Boston Bruins on the morning of draft day. Boston sent superb young defender Dougie Hamilton to the Flames in exchange for three draft picks. 

What Is The Immediate Impact? The Flames did the almost impossible—adding a young franchise cornerstone defenseman about to enter his prime—without giving up anything from their current roster. It's an instant game-changer, manna from heaven for all Calgary fans. 

How Much Does it Improve the Team for 2015-16? It is the most prominent move in a summer of exceptional acquisitions. Hamilton's addition to the Flames gives them significant help in an area where the club needed it. A year ago, Calgary rode the pairing of Mark Giordano and T.J. Brodie heavily, but this one trade gave them the kind of depth at defense few teams enjoy. It's an earth-shattering move that will impact the entire Western Conference. 

2. Los Angeles Kings Acquire Milan Lucic

Winslow Townson/Associated Press

What's The Deal? The Los Angeles Kings made a big deal with the Boston Bruins on draft day. The league's top power forward—Milan Lucic—headed to California for goalie Martin Jones and a package that included the No. 13 overall pick in the 2015 draft. 

What Is The Immediate Impact? The Kings are a big, heavy team that is no fun to play against every shift. Their big forwards on the skills lines—men like Anze Kopitar and Jeff Carter—punish opponents physically and on the scoreboard. Lucic will fit in perfectly, and the amount of possible damage done by these big men will be substantial.

How Much Does it Improve the Team for 2015-16? Some of the Kings' problems have come from offensive downturns by forwards like Dustin Brown and Mike Richards. Lucic is in his prime, plays the same physical style and can be expected to help spike the offense and the carnage this season.

1. Penguins Acquire Phil Kessel

Timothy T. Ludwig-USA TODAY Sports

What's The Deal? The Pittsburgh Penguins dealt a package of players, including top prospect Kasperi Kapanen, to the Toronto Maple Leafs for Phil Kessel.

What Is The Immediate Impact? The Pittsburgh Penguins sent a big message to the rest of the NHL in acquiring Kessel. The club has the strongest depth chart at center in the league but lacked an elite sniper on the wing to cash the chances created by Sidney Crosby or Evgeni Malkin. This trade changes that perception in a big way.

How Much Does it Improve the Team for 2015-16? It's reasonable to suggest Kessel will score 40 goals on Crosby's wing if both players are healthy all year. That's a major improvement, and there are other benefits for Malkin's line. If opponents are focused on Crosby, Malkin and his linemates—including quality wingers like Patric Hornqvist—will have easier minutes and can have a larger impact.

Note: All advanced stats courtesy Stats.HockeyAnalysis.com, cap information via NHLNumbers and player stats from hockeydb.