Shattenkirk-Williams-Hanzal

A look at underlying numbers can provide insight on what kind of impact a free agent can have on his new team.
Here are five interesting stats about some key players signed during Day One of NHL free agency:

Kevin Shattenkirk, D, New York Rangers

The Rangers added one of the NHL's highest-scoring defensemen on the power play. He was a big reason the St. Louis Blues' power-play success of 21.1 percent over the past four seasons was tied with the Pittsburgh Penguins for second in the NHL, behind the Washington Capitals (23.4 percent).
Shattenkirk and Erik Karlsson of the Ottawa Senators are the only NHL defensemen to score at least 25 power-play points in each of the past four seasons and more than 100 power-play points in that time.
Shattenkirk's 6.85 points per 60 minutes over the past four seasons led NHL defensemen, by 1.25 points per 60 minutes over Shea Weber of the Montreal Canadiens and Kris Letang of the Pittsburgh Penguins, who were tied for second with 5.60, according to the data compiled at Hockey Analysis.

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Justin Williams, RW, Carolina Hurricanes

Williams is valuable not only for his timely scoring but for consistently putting his team at an advantage in shot attempts.
Shot-based data goes back to the 2009-10 season on NHL.com. Since then, Williams' teams have outshot its opponents 8,232-6,086 with him on the ice, in terms of 5-on-5 shot attempts. That works out to an SAT of plus-2,146 that ranks fourth in the NHL.
Putting this information in other terms, his team's share of all on-ice shot attempts increases from 52.0 percent to 57.5 percent with Williams on the ice. That works out to a Relative SAT percentage of plus-5.5 that ranks 15th among the 1,217 players to play at least 50 NHL games.

Karl Alzner, D, Montreal Canadiens
Dan Girardi, D, Tampa Bay Lightning

July 1 was a busy day for defensive specialists like Alzner and Girardi. There aren't many statistics that measure defensive contributions, but Alzner and Girardi rank well among those that do.
Over the past seven seasons, Girardi led the NHL with 1,265 blocked shots, and Alzner ranked fifth with 1,048. Alzner's 1,475:19 of shorthanded ice time ranked sixth, ahead of Girardi (1,467:17).
Their tough defensive assignments left each defenseman with below-average shot-based metrics. Since 2009-10, Girardi's Relative SAT percentage of minus-4.1 percent ranks 251st among the 259 active defensemen to play at least 50 games, and Alzner's ranks 208th at minus-2.1 percent.

Radim Vrbata, RW, Florida Panthers

Vrbata, who scored 55 points (20 goals, 35 assists) in 81 games for the Arizona Coyotes, had the most points last season of any unrestricted free agent forward. He was the only Coyotes player to score 20 goals or 40 points.
With an Arizona-leading 233 shots, Vrbata topped 230 for the seventh time in the past 10 seasons, which is exceeded by only Alex Ovechkin of the Washington Capitals (nine).
Vrbata may prove most useful to the Panthers in the shootout, where he leads the NHL with 45 goals on 104 attempts, a success rate of 43.3 percent.

Martin Hanzal, C, Dallas Stars

Hanzal is the type of versatile, do-it-all player who can be inserted anywhere in the lineup and contribute in almost any game situation.
Hanzal has averaged 0.52 points per game in the NHL, has 84 power-play points, has averaged 1:37 minutes per game killing penalties, and has thrown 2.3 hits per game.
Over the past three seasons, Hanzal has won 1,699 faceoffs and lost 1,320, for a .563 winning percentage that ranked 11th among the 145 NHL players to take at least 1,000 faceoffs in that time.