Using similarity scores to compare defencemen

Travis Yost

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Monday’s article on Vancouver Canucks forward Brock Boeser and his impressive rookie campaign prompted a series of questions about similarity scores and how we might be able to apply it to other forwards around the league.

I ended up spending most of Monday talking with readers about other forwards who shared comparable seasons. I was fascinated to find out how statistically similar Nick Bonino and Matt Nieto were in 2017-18. I was just as fascinated to learn how statistically dissimilar Jeff Skinner and Brian Gibbons were.

Sadly, I couldn’t satisfy any requests for defencemen. I simply hadn’t included them in the comparison. Because it’s early August and I can get away with it, I wanted to re-introduce the topic of similarity scores and use today’s piece to talk about some of the interesting findings across NHL blueliners.

As a quick refresher, reference Monday’s note on the creation of similarity scores:

There is a bunch of ways of creating similarity scores or comparable player profiles. I prefer to create a series of z-scores – the number of standard deviations from the mean a data point is – for a series of statistical measures. In the immediate case, I referenced measures related to individual player production (think scoring rates, shooting percentages, penalties drawn, shot generation) and on-ice performance (how shots and goals fell with the player on the ice, deployment, etc.). Then, I created quick lookup tables to match players with comparable statistical backgrounds.

The table below is on a -1 to 1 scale. A -1 would indicate the two players had very little in common, statistically speaking. A 1 would indicate the two players had virtually identical seasons.

The table at the bottom of the page shows both the most similar and most dissimilar statistical comparables for every defender last year, minimum 400 minutes played. Review at your own leisure. Again, keep in mind that these are descriptive measures and really a tool for benchmarking more than anything else.

A few thoughts, in no particular order:

- Two defensive pairings were virtually indiscernible from one another. In Carolina, it was Brett Pesce and Jaccob Slavin (0.88), and in Calgary it was Dougie Hamilton and Mark Giordano (0.87). Considering the sheer number of minutes these guys played together at 5-on-5, that’s not a surprise. What is interesting though is there were a number of non-teammates who were just as statistically comparable. Philadelphia’s Travis Sanheim and Vegas’ Colin Miller (0.85) also had remarkably similar seasons on a rate basis, as did Dallas’ John Klingberg and Toronto’s Travis Dermott. Obviously the latter flatters Dermott – who played 37 games in his rookie season – quite a bit, but I also think it speaks to how effective the Leafs were offensively with him on the ice. I fully anticipate Dermott seeing a full NHL season next year, probably moving around between Toronto’s second and third pair. (For what it is worth, Dermott also saw very comparable results to Boston’s Matt Grzelcyk and Philadelphia’s Shayne Gostisbehere.

- I love looking at players who have completely different roles – usually it involves a very defence-oriented blueliner with limited offensive production against a player who is very aggressively deployed in softer offensive zone minutes. The biggest polar opposites last year were Ottawa’s Ben Harpur and Philadelphia’s Gostisbehere (-0.86). Other honourable mentions include Anaheim’s Kevin Bieksa and Nashville’s Ryan Ellis (0.85), and Anaheim’s Hampus Lindholm versus Los Angeles’ Dion Phaneuf (0.84).

- I was also curious to look at who most closely compared to some of the league’s former Norris Trophy winners:

Zdeno Chara: Dougie Hamilton (0.69) and Dustin Byfuglien (0.60)

Duncan Keith: Andrej Sekera (0.77) and Oscar Klefbom (0.71)

Erik Karlsson: Jaccob Slavin (0.68) and Collin Miller (0.62)

P.K. Subban: Matt Dumba (0.75) and Matt Niskanen (0.66)

Drew Doughty: Mattias Ekholm (0.76) and Hampus Lindholm (0.67)

Brent Burns: Seth Jones (0.73) and Colton Parayko (0.70)

Victor Hedman: Ivan Provorov (0.78) and Zach Werenski (0.68)