Top free agent centers: Martin Hanzal, Joe Thornton set to hit market

Having a strong foundation up the middle of the ice is crucial when building a Stanley Cup contender. The Pittsburgh Penguins have certainly proven that by winning back-to-back championships.
With the NHL Expansion Draft and the 2017 NHL Draft over, the attention shifts to July 1, when general managers can attempt to bolster their rosters by signing unrestricted free agents.

RELATED: [Top free agent wings set to hit market | Top free agent defensemen to hit market]
NHL.com takes a closer look at the top UFA centers expected to be available when the market opens Saturday:

Martin Hanzal, MIN

Hanzal, 30, set an NHL career high in goals (20) and combined for 39 points with the Arizona Coyotes and Minnesota Wild this season. He had 13 points (four goals, nine assists) in 20 regular-season games for the Wild after being acquired from the Coyotes on Feb. 26.
Hanzal (6-foot-6, 226 pounds) is a big, solid, two-way center and has won 56.3 percent of his faceoffs over the past three seasons.
Hanzal was the Coyotes' first-round pick (No. 17) in the 2005 NHL Draft. He has 326 points (121 goals, 205 assists) in 628 NHL games with the Coyotes and Wild.
Possible landing spots: New York Rangers, New York Islanders, Montreal Canadiens, Penguins, San Jose Sharks

Joe Thornton, SJS

It's hard to envision Thornton playing for anyone but the San Jose Sharks; he has spent the past 11 1/2 seasons with them. But Thornton, who turns 38 on Sunday, appears to be hitting the open market.
Thornton, who helped the Sharks reach the Stanley Cup Final for the first time in 2016, scored seven goals this season but still managed to get 50 points in 79 games and won 50.9 percent of his faceoffs. He had two assists in four games in the 2017 Stanley Cup Playoffs, when the Sharks lost in the Western Conference First Round against the Edmonton Oilers.
In 1,446 NHL regular-season games with the Sharks and Boston Bruins, Thornton has 1,391 points (384 goals, 1,007 assists). He has 123 points (27 goals, 96 assists) in 160 playoff games.
Possible landing spots: Sharks, Los Angeles Kings, Anaheim Ducks, Arizona Coyotes, Vancouver Canucks, Vegas Golden Knights, Toronto Maple Leafs, Nashville Predators, Rangers, Islanders, Penguins

Brian Boyle, TOR

Any team looking to take that elusive next step could use a player like Boyle, who has played in 73 playoff games over the past four seasons, including trips to the Cup Final with the Rangers (2014) and Tampa Bay Lightning (2015).
Boyle did not score a goal in 21 games for the Toronto Maple Leafs after being acquired from the Lightning on Feb. 27 but he did win 51 percent of his faceoffs. His experience helped Toronto clinch a playoff berth for the first time since 2013.
Boyle, 32, has 169 points (93 goals, 76 assists) in 624 NHL regular-season games and 28 points (15 goals, 13 assists) in 106 playoff games with the Maple Leafs, Lightning, Rangers and Kings.
Possible landing spots: Golden Knights, Ducks, Coyotes, Sharks, Bruins, Penguins, Lightning, Oilers

Nick Bonino, PIT

Bonino, 29, is coming off his second straight Stanley Cup championship with the Penguins. He had 37 points (18 goals, 19 assists) in 80 regular-season games and seven points (four goals, three assists) in 21 playoff games.
Bonino won 48 percent of his faceoffs this season but was a weapon on special teams; he had six goals and five assists on the power play.
Possible landing spots: Sharks, Kings, Vancouver Canucks, Coyotes, Canadiens, Rangers, Nashville Predators

Mike Fisher, NSH

Fisher, who turned 37 on June 5, had a productive season with 42 points (18 goals, 24 assists) in 72 regular-season games and helped the Predators reach the Stanley Cup Final for the first time. He had four assists in 20 playoff games.
It is hard to see the husband of country singer Carrie Underwood leaving Nashville, but it will be interesting to see which teams are interested in signing him.
Fisher has 585 points (276 goals, 309 assists) in 1,088 NHL regular-season games with the Predators and Ottawa Senators. He has 51 points (23 goals, 28 assists) in 134 playoff games.
Possible landing spots: Predators

Sam Gagner, CBJ

The Columbus Blue Jackets took a chance on Gagner when they signed him to a one-year, $650,000 contract in August. It worked out for both sides; Gagner had an NHL career-high 50 points (18 goals, 32 assists) in 81 regular-season games to help Columbus make the playoffs.
But what does Gagner, 27, do now? Does he re-sign with Columbus, which he knows is a good fit? Or does he sign a more lucrative contract elsewhere?
Possible landing spots: Blue Jackets, Rangers, Predators, Canadiens, Penguins, Canucks

Dominic Moore, BOS

Moore, who will turn 37 on Aug. 3, remains durable; he's played 80 or more games each of the past three seasons and had 25 points (11 goals, 14 assists) for the Boston Bruins in 2016-17.
Moore is solid in the circle too -- he won 54.6 percent of his faceoffs this season -- and is an asset on the penalty kill.
Moore has 270 points (100 goals, 170 assists) in 847 NHL regular-season games, and 29 points (12 goals, 17 assists) in 99 playoff games with the Bruins, Rangers, Sharks, Lightning, Canadiens, Buffalo Sabres, Maple Leafs, Wild and Penguins.
Possible landing spots: Penguins, Bruins, Carolina Hurricanes, Golden Knights, Coyotes, Ducks