Breaking down differences in NHL defence corps by looking at offensive and defensive impacts

Inspired by the recent excellent play of the Calgary Flames and especially by MacKenzie Weegar and the rest of the defencemen, I decided to take a look at how Calgary’s defence corps alone stacks up against the rest of the league.

As far as scoring points has gone this season for Calgary, it has been a job for the committee. There is no one player on the Flames with an impressive point total, Nazem Kadri leads the team with 44 points but that is tied for 51st in the league. Despite the poor individual totals, the Flames are in fact 14th in the league in goals scored. Though that is not where the Flames faithful would like them, it is far from disastrous.

Calgary’s defence is providing offence

A huge reason for the half-decent goals total is the defence corps. The Flames are one of a few teams to have three defencemen in the top ten in scoring on the team and are the only team in the league to have three defencemen in the top 25 in goals scored by defencemen—a list that Weegar now sits atop. That $6.25 million price tag hanging from his lapel is really starting to look reasonable. As an interesting aside, according to CapFriendly.com, Weegar hasn’t scored this many goals in a season since before he could legally drive.

The other two impressive gentlemen, Noah Hanifin (nine goals), and Rasmus Andersson (seven goals) have a very good chance at breaking their season goal totals as well. Although recently the Flames goal scorers have looked more capable in general, the Flames would be in truly awful shape without the scoring prowess of their blue line. Here is a look at how the Flames defenders compare to the rest of the defence corps in the league.

NHL defence corps by offence versus defence

If you can’t find Calgary, it’s because they’re stubbornly stuck behind the Nashville Predators, a lot like the current NHL standings.

Here’s what the charts represent:

The top six defencemen based on ice time on every team are aggregated and compared as an entire defence corps against other teams. The offence and defence are compared using a derived model that takes metrics from both ends of the ice.

I endeavoured to score each team’s blueliners from 0–100 in both offence and defence. Offensively, the defencemen are judged on points/60, shots/60, and expected goals/60 so you might think of it as a measure of how much they actually produce as well as how many opportunities they help provide. However, since it’s much better to have actual goals than just opportunities, the offensive score is weighted toward points.

True defensive effectivity is very difficult to quantify but here they are ranked by high-danger scoring chances against, giveaways, blocked shots, and hits; with the first two counting against them. This defence score is weighted towards high-danger scoring chances since limiting those is probably the most important job for defencemen and for the whole team for that matter. This is why HDSCA is not a perfect metric of a defenceman—they can only do so much by themselves. The other stats are at least more concrete—it’s easy to see how helpful a timely blocked shot and hit, or how disastrous a turnover can be, and just as easy to see who’s responsible. For that reason, the defence score is not as heavily weighted towards HDSCA as the offence is towards points.

The Flames find themselves in a relatively reassuring spot, though the disconnect between this graph and the standings serves as a reminder that this is only a ranking of the defencemen (and only the top six in ice time for each team), and that statistics can only take you so far.

Isolating goal impacts by defence corps

Focusing purely on goals doesn’t change the graph as much as I had thought it might, but here it is for your inspection anyhow. At the very least it moves the Flames out from under the paw of the Predators (a fitting analogy for how they can pass them in the standings).