Defense isn't resting for conference finalists

The importance of a strong No. 1 defenseman in the Stanley Cup Playoffs can't be overstated. In the recent past, Duncan Keith of the Chicago Blackhawks, Drew Doughty of the Los Angeles Kings and Zdeno Chara of the Boston Bruins each has played a critical role in the success of his team.
True to this history, the four 2016 conference finalists all have a dominant No. 1 defenseman who excels in at least one aspect of the game.

According to the numbers, Brent Burns of the San Jose Sharks generates scoring at an elite level, Kris Letang of the Pittsburgh Penguins drives the puck-possession game, Alex Pietrangelo of the St. Louis Blues shuts down top opponents in tough, defensive situations, and Victor Hedman of the Tampa Bay Lightning is a complete defenseman who contributes in all three categories.
Burns generates scoring
San Jose's edge is having a puck-moving defenseman who can produce a lot of offense.
Burns has scored 18 points in 14 games, most among defensemen in the playoffs by a wide margin (John Carlson of the Washington Captials is second with 12 in 12 games) and second to teammate Logan Couture (19 points) in the NHL.
In the regular season, Burns scored 75 points, second among defensemen to Erik Karlsson of the Ottawa Senators (82).
Burns continues to hold the lead even when opportunity is taken into account, with a scoring rate of 2.0 points per 60 minutes at even strength and an amazing 10.1 with the man-advantage.
Letang drives possession
Scoring is one of the keys to playoff success, but it's equally important to balance those extra scoring chances by denying them to opponents.
The Penguins have the edge in this regard because of the ease with which Letang transitions the play out of Pittsburgh's zone and drives it up the ice. That's why the Penguins are outscoring their opponents 15-9 while Letang has been on the ice at even strength, and 25-13 in all manpower situations, the second-largest margin among the League's defensemen.
Because a good goal differential is a combination of shots and shooting percentages, and with defensemen not having a great deal of control over the latter, it makes sense to confirm the results using shot-based statistics. Even from this perspective, Letang remains one of the most dominant defensemen in the postseason.
In absolute terms, the Penguins have a 299-260 edge in shot attempts when Letang on the ice, for a differential of plus-39, which ranks third among defensemen.
Letang's importance to the Penguins is most evident when comparing how the team performs with him on the ice, relative to when he's not. Pittsburgh is responsible for 53.5 percent of all shot attempts with Letang, and 48.1 without him, for a Relative SAT of plus-5.4 percent, which ranks No. 5 among defensemen who have played at least 10 playoff games.
Pietrangelo plays the tough minutes
For the Blues, the edge is having a No. 1 defenseman like Pietrangelo who shuts down top opponents.

There are a number of ways a defensive player's contributions can be measured using statistics. For example, Pietrangelo has lined up for 145 faceoffs in the defensive zone, the most in the NHL. Factor in his 82 faceoffs in the offensive zone, and he has a zone start percentage of 36.1 percent, the eighth-lowest among defensemen.
Pietrangelo has spent 49:22 killing penalties, the highest total in the League. Ian Cole of the Pittsburgh Penguins (45:49), Valtteri Filppula of the Tampa Bay Lightning (45:23) and Hedman (41:24) are the other players who have played more than 40 shorthanded minutes.
Finally, some fans have used NHL's data to develop estimates of which players are taking on the toughest average opposing lines, and to which players' teams have turned to protect late leads, and Pietrangelo ranks near the top of each list.
Hedman does it all
Tampa Bay's advantage is having a defenseman like Hedman who can contribute in all the previously mentioned areas at a level not far removed from the League leaders.
Hedman has scored 11 points in 13 games, tied with Kevin Shattenkirk of the Blues for third among defensemen, and has a strong scoring rate of 1.8 points per 60 minutes at even strength and 4.1 with the man-advantage.
In terms of shot-based metrics, Hedman ranks just ahead of Letang with a Relative SAT of plus-7.1 percent.
Defensively, Hedman's 80 defensive zone starts rank second on the Lightning to Braydon Coburn (91), his 41:24 ice time spent killing penalties is fourth in the NHL, and he is coach Jon Cooper's first choice when protecting late leads or facing top opponents.