Zone Exits: An introduction

Kent Wilson
August 14 2013 09:29AM

 

 

By: Pierce Cunneen

Most readers here may be familiar with the Zone entry project. For those who aren't, check out this article by Eric T from NHL numbers. Short version: a group of bloggers for the past few years have taken it upon themselves to track Neutral zone performance for several teams.

The results of such work has been incredible, and we are learning that the neutral zone is far more important than we previously assumed.

And while there is still much work to be done with continued tracking of zone entries (if you are interested in helping track zone entries, shoot me an email at pcunneen19@gmail.com, tweet me at @pcunneen19, or tweet Eric at @BSH_EricT), a few of us have decided to take a closer look at the defensive zone.

Specifically, we would like to focus on zone exits. Zone exits are anytime a defending team is able to clear the puck out of their defensive zone. Zone exits are undoubtedly a very important aspect of hockey, and understanding them better may help lead us to better understand defensive performance.

Why You Should Care

For one thing, you will be changing our understanding of hockey. The zone entry project has helped revolutionize our understanding how teams dominate play and what can be the difference between winning and losing. We have that same opportunity with tracking zone exits.

This is also an opportunity for you to learn some amazing things about your favorite team. Learn who moves the puck more between a pair of D-men, which defensemen are turnover machines, or which D-men are a detriment when it comes to moving the puck with possession out of the D-zone.

All these questions can be answered by tracking zone exits.

So How does one Track Zone Exits?

It's not too complicated. All you have to do is watch a game and record when a team sends the puck out of their defensive zone, noting the time, the player, the exit type, whether the play was pressured by the opposition, and the strength (5v5, 5v4, 4v5, etc). For exit type, all you have to do is write down a one letter or two letter code depending on how the puck was advanced across the defending blue line (C=carry, P=pass, Ch=chip, etc).

Below is an example of the first minute of the Rangers vs Flyers game this past season that I recorded:

Period Time Exit type Player Pressure? Strength
1 19:55 P 8 YES 5V5
1 19:45 C 8 YES 5V5
1 19:27 CH OPP YES 5V5
1 19:15 I OPP YES 5V5
1 19:05 P OPP YES 5V5

That's all there is too it. Just like with the zone entry project, we have decided to not record the opponents numbers (in order to save time, since most fans can't recognize players from other teams very easily). There are a few other things we excluded/included, and if you are interested in joining the zone exit tracking project I can fill you in on those things.

So what can we do with this info. Well for one, we can evaluate players based on how often they clear the defensive zone and how often they clear the zone with possession. We can also evaluate teams. Once we get enough data from enough teams, we can determine how often "good teams" are able to exit the defensive zone with possession.

We can also link up zone exit data with zone entry data and figure out how often certain types of exits generate zone entries with possession/without possession.

So if you have a NHL game center account or can record NHL games on a TV and want to learn a bunch about your favorite team and/or want to make an impact on our understanding of hockey, shoot me an email at pcunneen19@gmail.com or tweet me @pcunneen19 to get all the information on either zone entry tracking or zone exit tracking. I will further explain the process of zone entry/exit tracking and what you need to do.

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Former Nations Overlord. Current FN contributor and curmudgeon For questions, complaints, criticisms, etc contact Kent @ kent.wilson@gmail. Follow him on Twitter here.
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#1 Pierce Cunneen
August 15 2013, 01:56PM
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Also, we have openings for people who can only track half a season or so. You won't be required to track all 82 games if you join the tracking project.

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#2 Pierce Cunneen
August 14 2013, 10:23AM
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PopsTwitTar wrote:

I think this is a great idea. For a "pass" does it have to be completed to count? I think one of the things that is hard to determine is the skill in making a good pass compared to the skill in collecting a tough pass.

We have three classifications for passes. One is a completed pass, the second is a pass that gets out of the zone but either misses the target or hits the guy in the skate or for some reason doesn't get to the target. The third is a pass that is turned over in the defensive zone

So the first code would count as a successful exit with possession

The second code would count as a successful exit without possession

and the third code is an unsuccessful exit

So there is still some subjectivity in the tracking, but I have tried to eliminate it as much as possible.

It's not a perfect system whatsoever, but hopefully it is thorough enough to give us some good results

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#3 leafer4life
August 14 2013, 11:02AM
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How about a "to the line and not out" failed zone exit? The leafs have mastered this defensive strategy.

More seriously, in the past the leafs employed wingers who avoided contact on the side boards and so were not successful chipping the puck out. I question if focusing on the player trying to clear the zone tells the correct story.

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#4 Hand Knit
August 15 2013, 05:25AM
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I'm curious if if "pressure/no pressure" could be more finely broken down. As is, the current system considers all pressure equal: a lone forechecker chasing a dump-in that forces the tracker to make a judgement call on whether or not they're really pressuring the puck is considered to exert just as much pressure as a team fully established in the offensive zone, with the puck behind the net. Cutting up zone exits by type of zone entry faced might make some sense, so we would have something like the following:

(1)Opposition zone entry by dump in (2)Opposition zone entry with possession (3)Defensive zone faceoff, won (4)Defensive zone faceoff, lost

No idea whether or not there would be meaningfully different results, but it seems plausible.

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#5 PopsTwitTar
August 14 2013, 09:54AM
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I think this is a great idea. For a "pass" does it have to be completed to count? I think one of the things that is hard to determine is the skill in making a good pass compared to the skill in collecting a tough pass.

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#6 Pierce Cunneen
August 14 2013, 11:08AM
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leafer4life wrote:

How about a "to the line and not out" failed zone exit? The leafs have mastered this defensive strategy.

More seriously, in the past the leafs employed wingers who avoided contact on the side boards and so were not successful chipping the puck out. I question if focusing on the player trying to clear the zone tells the correct story.

We are also calculating On ice stats, so we will be able to see when for example Phil Kessel is on the ice, what % of exits occurred with possession vs without possession

We also are calculating team stats as well.

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#7 gongshow
August 15 2013, 12:15AM
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Kent, I'm excited to see how this one turns out.

Also, to maybe give you an idea based upon my own experience...

I'm not sure how you're planning to link the Zone Exits to the Zone Entries, but when I tracked Zone Exits and Entries for my son's team, to simplify the tracking and quantification of the end result of each Zone Exit, I simply added a tick (+1) for each line gained before turning over possession. For example: over the blue = +1, over center = +2, Ozone entry = +3 and a shot or puck entering the slot as +4.

In my tracking system (using minor hockey rules), I could never figure out what to do with icing in terms of assigning a value, so I always pulled those events out as a separate group. In my mind, an NHL game that restricts a line change and brings the puck back into the Dzone for a 50/50 faceoff could be assigned either a 0 a -.05 or a +0.5.

Also I added a code to the Zone Exit and Entry so that I could see (for example) that if the puck was passed out over the Dzone blue it was carried in on the Zone entry. Adding jersey numbers to the events at the Blue lines helped as well but started to create alot of confusion during a live game without rewind. Center Ice would make this easier obviously.

I'd love to learm more about your current project and help out, but my schedule won't allow it this coming season.

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#8 Pierce Cunneen
August 15 2013, 08:42AM
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Hand Knit wrote:

I'm curious if if "pressure/no pressure" could be more finely broken down. As is, the current system considers all pressure equal: a lone forechecker chasing a dump-in that forces the tracker to make a judgement call on whether or not they're really pressuring the puck is considered to exert just as much pressure as a team fully established in the offensive zone, with the puck behind the net. Cutting up zone exits by type of zone entry faced might make some sense, so we would have something like the following:

(1)Opposition zone entry by dump in (2)Opposition zone entry with possession (3)Defensive zone faceoff, won (4)Defensive zone faceoff, lost

No idea whether or not there would be meaningfully different results, but it seems plausible.

I like your idea on looking at zone exits after certain plays (such as dump ins or face-offs. This is something we might look at towards the end of the season, once we have a lot of data. Shouldn't be too hard to look at since we will have access to PBP sheets for all teams and zone entry data for certain teams

Good idea!!

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#9 Robert Vollman
August 16 2013, 01:06PM
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Sweet - I'm very excited to hear about this zone exit project!

I still remember when Corey S broke down the 2012 Stanley Cup final between the Kings and the Devils using zone exits, and was hoping someone would run with it. VERY cool stuff.

It was actually right here on NHL Numbers, I dug up the link. I see you have changed the methodology slightly so it's a little easier to track.

http://nhlnumbers.com/2012/6/14/2012-stanley-cup-final-zone-exits

Good luck with all of this, I can't wait to see the results. How many teams do you have covered?

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#10 Pierce Cunneen
August 16 2013, 01:18PM
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Robert Vollman wrote:

Sweet - I'm very excited to hear about this zone exit project!

I still remember when Corey S broke down the 2012 Stanley Cup final between the Kings and the Devils using zone exits, and was hoping someone would run with it. VERY cool stuff.

It was actually right here on NHL Numbers, I dug up the link. I see you have changed the methodology slightly so it's a little easier to track.

http://nhlnumbers.com/2012/6/14/2012-stanley-cup-final-zone-exits

Good luck with all of this, I can't wait to see the results. How many teams do you have covered?

As of now we have 28 teams covered. Now that doesn't mean every single tracker will stay with the project the entire year, but I'm hoping to get as many people on board so that we have back up trackers in case some of my trackers find it too much of a time commitment.

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#11 Robert Vollman
August 16 2013, 01:21PM
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Pierce Cunneen wrote:

As of now we have 28 teams covered. Now that doesn't mean every single tracker will stay with the project the entire year, but I'm hoping to get as many people on board so that we have back up trackers in case some of my trackers find it too much of a time commitment.

28? Holy cow. That's amazing. Good work.

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#12 Benhur
August 19 2013, 08:11AM
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Last season I was tracking Own Zone Turnovers (OZT) by the Oilers and their opposition. One of the glaring problems I have seen with the Oilers were the amount of turnovers they were giving up in their own zone. As you can probably guess, the Oilers were woeful at moving the puck out under control. One game I remember with the Blues the Oilers had about 30 OZT to the Blues 1. OUCH!!! After observing this for most of the season I came to the conclusion that the problem was in their breakout system and coaching primarily. Also that even with a poor OZT ratio in a game the Oilers still managed to win a few...such as the above Blues game where thet won, I believe, 3 - 1. You may want to incorporate this into your data collection as it is directly linked to your project. What I called an OZT was when a player had control of the puck in his own zone and gave up that puck to the opposition on a forecheck or poor pass, etc.

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#13 Badger M
August 26 2013, 10:34AM
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leafer4life wrote:

How about a "to the line and not out" failed zone exit? The leafs have mastered this defensive strategy.

More seriously, in the past the leafs employed wingers who avoided contact on the side boards and so were not successful chipping the puck out. I question if focusing on the player trying to clear the zone tells the correct story.

As much as everyone loves to bash the Leafs, they were the best team in the playoffs at maintaining control during zone entries.

http://www.shutdownline.com/hurricanes/statistical-analysis/tracking-the-playoffs-zone-entries.html

Thank you Kessel.

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