About a month ago, reader @AustinBolts asked Kyle Alexander and me on twitter what difference Hedman made for the Lightning. At the time Hedman was about a week or so into what was to be a two-week absence, and the team was struggling a bit. This is a question that's hard to untangle. There are a lot of variables, not least of which is that there were other defensemen out at the same time, most notably Hedman's most frequent partner Sami Salo.

I put it on my list of things to look at and meant to have it as part of my last ten-game stats report, but that went long enough as it was so I've made this a separate post.

First at the team level:

Team record: Hedman missed 6 games in December. Without him they went 3-1-2 (.666 points percentage, .500 win percentage). With him in the lineup, the team has gone 24-13-2 (.641 points percentage, .615 win percentage). So they were losing games but still gaining points.

In the games he played the team did well at controlling the puck when the score was close, despite eventually losing three of those games. This is part of a larger pattern of the team as a whole improving at 5v5 puck possession over the month of December.

On the surface, it seems that the team...well, more or less went on without him. That seemed odd to me, given the strength of what Hedman's doing compared to the league as a whole. He has the best relative Corsi numbers among Lightning defensemen, and Kyle recently showed how well Hedman's doing in many, many areas, including scoring and possession.

I looked at his WOWYs, which is stathead slang for With or Without You analysis, to see who he plays with and get some idea of how he affects their results. The following table lists his teammates in order of the amount of time they play with Hedman:

Here we see that at when we include all 5v5 time, regardless of score, almost everyone gets better results playing with Hedman than they do playing without him. This is especially true of puck possession, but really, across the board, everyone does something better with Hedman both on offense and on defense.

Nate Thompson and Alex Killorn are helped all around. Tyler Johnson, Ondrej Palat, and Andrej Sustr are particularly helped in possession, Sustr in possession for and Johnson and Palat in possession against. But really, everyone's better except Martin St. Louis and Ryan Malone, and since Malone was one of the few players not helped by Steven Stamkos's offensive play, I'm beginning to think he's a possession weirdo. (There is no denying that Malone plays better with Thompson and B.J. Crombeen than he does with any other forwards and better with Andrej Sustr than with any other defenseman.)

But let's take a look at Hedman's 5v5 Close WOWYs.:

Hedman's effect at Close (ZSADJ) GF20 GA20 GF% CF20 CA20 CF% Sami Salo 0.326 0.53 -20.5 -2.65 -0.7 -2.4 Martin St. Louis 0.143 0.423 -11.7 -3.63 -0.4 -4.2 Valtteri Filppula 0.916 0.394 9.1 1.72 0.69 0.9 Alex Killorn 0.271 0.417 -6.6 -3.11 1.92 -6.8 Ondrej Palat -0.493 0.043 -15 -3.06 -7.73 8.2 Tyler Johnson -0.174 0.27 -16.2 -2.38 -6.12 6.7 Teddy Purcell 0.391 0.427 -4.4 3.3 1.25 1.6 Richard Panik -0.167 -0.905 22.7 -3.74 -5.5 3.2 Andrej Sustr 1.001 0.02 30.3 3.86 3 0.5 Nate Thomspon 1.291 0.471 4.7 -1.54 -3.33 3.3 Steven Stamkos 0.176 0.152 -1.1 -2.41 -0.01 -3.4 Ryan Malone -0.215 0.617 -22.5 -0.77 4.44 -7

When the score is close Hedman's effect on other players' possession numbers are less drastic but still good. Here, the benefits of playing with Hedman are coming almost entirely in Goals For and shot attempts against. Again, Palat and Johnson see great bumps in possession against when Hedman's supporting them, and Andrej Suster and Nate Thompson get better offensive results with Hedman. And now Richard Panik shows up as a beneficiary of playing with Hedman.

Marty St. Louis seems to do a little better when Matt Carle is on the ice than he does with Hedman, but the difference is small (a difference of 3% in goal scoring and 2% in possession.) And St. Louis and Carle play together more frequently than St. Louis and Hedman do, so it seems that this is already recognized by the coaches.

Overall, it appears that the improvement in possession since December is driven not simply by whatever improvements Victor Hedman has seen since last season. Hedman makes a huge difference in possession for almost everyone he plays with and that benefit comes both offensively and defensively. And he's signed for three more years at a $4M cap hit, which may be one of the best contracts Steve Yzerman has yet done.