How Do Defensemen Impact Ryan Nugent-Hopkins?
After a recent article comparing Ryan Nugent-Hopkins, Gabriel Landeskong and Sean Couturier, Woodguy made a comment speculating that the quality of defensemen playing behind these rookie forwards might be influencing their results. Here is elite recruiter Derek Zona's reply, which shows the ice time for defensemen playing with each of those three. Using my database, I looked at Nugent-Hopkins's numbers with each defenseman. The results were pretty interesting.
There was a very strong pattern, with RNH putting up decent numbers in front of the better defensemen and really struggling with the weaker ones. To measure this I use a different method for adjusting for zone starts than DZ does, which I've outlined here. Unfortunately, they're both called zone start adjusted Corsi (ZSAC), the most obvious name to give to a metric that adjusts Corsi for zone starts. Zero represents what a team of average players would get with the same type of ice time.
The Oilers haven't kept their pairings together too consistently, so I'm just putting the numbers up for each individual defenseman. Here are Ryan Nugent-Hopkins's ZSAC numbers with each defenseman:
| Player | TOI (mins) | ZSAC |
| Tom Gilbert | 170.3 | -0.733 |
| Ladislav Smid | 150.4 | 2.99 |
| Theo Peckham | 149.1 | -11.54 |
| Jeff Petry | 137.7 | -0.827 |
| Corey Potter | 118.7 | 2.689 |
| Andy Sutton | 81.6 | -8.226 |
| Ryan Whitney | 68.4 | -21.136 |
| Cam Barker | 60.3 | -33.004 |
| Colten Teubert | 44.7 | -13.694 |
| Alex Plante | 11.9 | -46.987 |
Some of it is sample size, certainly we can ignore time with Alex Plante, but I was surprised by how much variation there is in these numbers. Eyeballing the names, the pattern is clear: with relatively good defensemen he put up decent possession numbers, right around and maybe even a little above league average. Then things drop off substantially and his stats are quite bad with the bottom-of-the-barrel guys.
Never one to be satisfied relying on intuition and name recognition, I took a closer look at the relationship between the skill of the blue liner, as measured in different ways, and Nugent-Hopkins's Corsi numbers. My first instinct was to look at the performance of the defensemen when RNH was off the ice. Here is the resulting WOWY plot. The horizontal axis is the defenseman's Corsi without RNH and the vertical axis his Corsi with RNH on the ice. In other words, the x axis shows how good the blue liner is and the y axis how well RNH did with playing in front of him.

There should be a relationship, but this is stronger than I had expected. The equation, with the slope at 1.4, makes it seem that the defensemen quality impacts RNH's stats more than it does the average player. This again comes through looking at the names. There are four blue liners that have better stats with RNH on the ice than off - Smid, Petry, Potter and Gilbert. Whitney, Peckham, Sutton, Teubert, Barker and Plante have better numbers with Nugent-Hopkins on the bench.
Another way to look at it is to compare Nugent-Hopkins's Corsi stats to the ice time, with the idea that Renney should be giving better players more ice time. I ran it for both TOI/60 and total TOI for the season to date. The relationship between total TOI and RNH's numbers is much stronger, which I think reflects guys that have been struggling with injuries or form.


We'd like to see bigger samples and similar analysis for other rookies, but it looks like Woodguy may be on to something here. While we normally think about protecting a young forward's even-strength minutes by giving him a lot of offensive-zone starts and weak opposition, putting him in front of strong defensemen looks important as well, at least in this case. How crazy will Derek's five-dimensional graphs be?
Follow Jared on Twitter @jaredlunsford
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This analysis is rather eye opening. Excellent work, Jared!
by TakeoutArtist on Jan 31, 2012 7:15 AM MST reply actions 1 recs
Wow, that’s a ton of work and very interesting results, thanks for this.
So putting NHL quality Dmen behind the kids will help them immensely.
Who knew? (answer: everyone except Lowe and Tambellini)
I await the announcement of the Cam Barker extension with bated breath.
If they trade Hemsky and maybe Gagner while extending Barker another lottery pick is on the way in the summer of 2013.
by Woodguy on Jan 31, 2012 7:46 AM MST reply actions 4 recs
Wait. That first graph is of the defencemen’s numbers WOWRNH. Thus, doesn’t that slope mean that Hopkins affects the defenders’ numbers more than average, and not the other way around?
SNN Sports - A theoretical Oilers blog (i.e. theoretically, I write stuff there). Link now 100% less broken.
Robertson's Rants - Exceedingly occasional, lengthy ramblings on hockey topics, hosted at Puck Podcast. And no, my name's not Doug.
Sorry, that was probably confusing. Part of the problem is that you can interpret things a couple ways.
To see his impact on them you would need to look at the difference between their numbers with him on and off the ice. In the graph this would be the difference between the x value and the y value. I actually did run a regression of this on the D-man’s Corsi and it came out positive, implying that RNH has a more positive impact the better the defenseman. It wasn’t significant, which is probably because it is based on a sample size of 9 players and some of the within-player sample sizes are pretty small. It’s not conclusive, but the pattern is that RNH and his linemates can improve an already decent group but perhaps can not drive play on their own.
If you want to look at it from the D-man’s perspective, the slope tells you how much a change in a defenseman’s Corsi without RNH affects his Corsi with RNH. They sound similar, but you aren’t directly comparing on the on/off but rather looking at how the off affects the on. It’s easier to look at it from Nugent-Hopkins’s perspective and say it’s how much a change in the D-man’s Corsi without him affects his Corsi rate with that defenseman.
I fear that made things less clear.
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In the graph this would be the difference between the x value and the y value.
This should be reversed. His impact on the defenseman is the difference between the y value and the x value.
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Yeah, I think I’m less clear on that now than when we started.
SNN Sports - A theoretical Oilers blog (i.e. theoretically, I write stuff there). Link now 100% less broken.
Robertson's Rants - Exceedingly occasional, lengthy ramblings on hockey topics, hosted at Puck Podcast. And no, my name's not Doug.
Yeah, sorry I overcomplicated it. The short of it is that if you want RNH’s effect on the D then it’s RNH on – RNH off. If you want to get the effect of their skill on his stats it’s the slope of that line.
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by JaredL on Feb 1, 2012 11:16 AM MST via mobile up reply actions
So what you’re saying is, the slope of the line reflects their ability to be affected by him, and thus indirectly is an indicator of their own ability to affect him?
SNN Sports - A theoretical Oilers blog (i.e. theoretically, I write stuff there). Link now 100% less broken.
Robertson's Rants - Exceedingly occasional, lengthy ramblings on hockey topics, hosted at Puck Podcast. And no, my name's not Doug.
Yeah, saying it’s there indirectly seems like a nice way to put it.
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I want to live in a world of five-dimensional ZSAC plots.
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by Chase W on Jan 31, 2012 1:52 PM MST reply actions 1 recs
Well, you can get it up to four if you make the fill be a gradient, and then size be something else. Not a sweet clue how you get five, unless you create a 3D bar plot and then apply the aforementioned.
SNN Sports - A theoretical Oilers blog (i.e. theoretically, I write stuff there). Link now 100% less broken.
Robertson's Rants - Exceedingly occasional, lengthy ramblings on hockey topics, hosted at Puck Podcast. And no, my name's not Doug.
We’d like to see bigger samples and similar analysis for other rookies, but it looks like Woodguy may be on to something here. While we normally think about protecting a young forward’s even-strength minutes by giving him a lot of offensive-zone starts and weak opposition, putting him in front of strong defensemen looks important as well, at least in this case.
Depending on the difficulty of generating these studies, I’d be interested in seeing more
Editor of The Copper & Blue, and leader of The Cult Of Hartikainen.
Yeah, I’m definitely planning on it. I’d like to run it for a couple more rookies and it’d be interesting to look at a year-by-year comparison for some players. It would make sense for rookies to be more sensitive to defensemen behind them than players with a few years under their belts, but maybe that isn’t the case.
Driving Play - The Blog with Three First Lines
by JaredL on Feb 1, 2012 8:00 AM MST via mobile up reply actions

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