McDonagh could make immediate impact with Lightning

With the acquisition of Ryan McDonagh, the Tampa Bay Lightning are among the NHL's best on defense, and have the depth, grit, and flexibility to counter the recent moves their top rivals have made offensively.
Prior to the NHL Trade Deadline on Monday, the New York Rangers traded defenseman McDonagh and forward J.T. Miller to the Lightning for forward Vladislav Namestnikov, prospects Libor Hajek and Brett Howden, a first-round pick in the 2018 NHL Draft and a conditional first-round pick in the 2019 NHL Draft.

For most of McDonagh's eight seasons with the Rangers, he was their top choice at defenseman. In that time, his average of 19:03 minutes per game at even-strength ranked first among Rangers defensemen, and his average of 2:38 shorthanded ranked second to Dan Girardi (2:53), who signed with the Lightning on July 1, 2017.
At even-strength, McDonagh has been used primarily in the defensive zone and against top opponents. His NHL career offensive-zone start percentage of 45.37 percent is the third-lowest among the 25 defensemen to play at least 20 games for the Rangers in that time, and his most frequent opposing forwards this season include Taylor Hall of the New Jersey Devils (22:28), Tom Wilson (21:03) and Alex Ovechkin (20:25) of the Washington Capitals, and Auston Matthews of the Toronto Maple Leafs (20:15), according to Natural Stat Trick.
Although defensive play is McDonagh's primary value, he contributes offensively. His 238 points (51 goals, 187 assists) in 516 games ranks 26th among defensemen since he made his NHL debut in 2010-11. He has averaged 1:51 minutes per game on the power play but is unlikely to be used there by Tampa Bay, which uses four forwards and one defenseman with the man-advantage, either Victor Hedman or rookie Mikhail Sergachev.

McDonagh adds to a defense that is already among the NHL deepest. The Lightning have used seven defensemen instead of six in 29 of their 62 games. Four teams have done so on more than four occasions this season (Ottawa Senators, 15; New Jersey Devils, nine; Detroit Red Wings, nine; Colorado Avalanche, seven).
McDonagh's arrival means Tampa Bay likely will continue to use seven defensemen, giving it added security in the third period if one or more of the defensemen have been injured, are fatigued, or are serving penalties.
Playing with seven defensemen allows for greater specialization of roles. For example, Sergachev's offensive zone start percentage of 69.40 percent at 5-on-5 ranks second among NHL defensemen to play at least 20 games, and Braydon Coburn's is fifth-lowest at 38.53.
To facilitate this specialization of roles, the Lightning's top two defensemen, Hedman and Anton Stralman, play leading minutes against top opponents, and often with a less experienced partner, Jake Dotchin or Sergachev. That is why there's a noticeable gap between Hedman and Stralman, who play 25:44 and 21:16 minutes per game, and the Lightning's No. 3 defenseman, Girardi (17:05).

The addition of a third top defenseman like McDonagh, who averaged 23:54 minutes per game with the Rangers this season, will help spread out that responsibility and increase the Lightning's flexibility.
The most likely deployment is to play McDonagh with Girardi, his former defense partner with the Rangers. This will give the Lightning three pairs with at least one top two-way defenseman and help defend against rivals who have constructed a third scoring line, such as the Pittsburgh Penguins with the addition of center Derick Brassard.
If Hedman continues to play with Dotchin, and Stralman with Sergachev, then this alignment makes each pair strong enough offensively to counter Toronto's construction of a second defensive line around newly acquired center Tomas Plekanec.
In other cases, an interesting option is for McDonagh to play with either Sergachev or Dotchin, which allows Hedman and Stralman to play together as they did in 2015-16, through the first half of 2016-17, and occasionally in recent games. That could be the right strategy for a power-versus-power matchup against teams like the Boston Bruins, who added Rick Nash to their top six but whose depth lines continue to include less-experienced scorers.