Quantifying Gretzky’s “Office” in The Modern NHL

If you start learning about Wayne Gretzky’s iconic hockey career, you will eventually hear about something called “the office.” The area behind the net was dubbed “the office” because it was where Gretzky wreaked havoc on opposing defenders and preyed on helpless goalies. By taking the puck behind the net, Gretzky forced the opposition to pay attention to him while turning their backs to his four other teammates. His spectacular play in “the office” is one of the reasons he tallied so many assists throughout his career. While teams have gradually adapted their defensive systems and tactics to control this area of the ice, the advantages of playing the puck behind the net in the offensive zone still exist. Courtesy of Ryan Stimson and the Passing Project, we can now analyze data from the 2015-16 season to see which forwards succeed by playing below the icing line.

Quantifying play within this area may seem complicated at first, but we can make it easier for ourselves by simplifying things as much as possible. While Gretzky’s “Office” was only the section of ice behind the net, we’ll expand our version of this space to include the entire area below the icing line.  We can be certain that every shot assist from below the icing line has two characteristics:

  • A player located below the icing line makes a pass to a teammate.

  • The recipient of the pass shoots the puck.

These two characteristics can now be quantified using the data released in the article linked above. Analyzing the data will tell us how often players make passes from “the office” (and elsewhere below the icing line) that lead to shots. We will also be able to see which players receive these passes and take the subsequent shots most frequently. Although we probably won’t find anyone as dominant as we’d expect Gretzky to have been, it is fun to look at the data nonetheless.

Lets begin by determining which forwards are the best at being sources of danger when they have the puck below the icing line. The metric that quantifies this is called Behind-the-Net Shot Assists per 60 minutes, or BtNSA/60 for short. In other words, a Behind-the-Net Shot Assist is any pass that originated below the icing line and led to a shot. We are looking at a sample of 282 forwards who played at least 300 minutes at 5v5 during the 2015-16 regular season games that have been tracked. Here is the top 15:

Screenshot 2017-03-06 15.03.22.png

The first thing I noticed is how good Henrik Sedin is. His 3.201 BtNSA/60 dwarfs the black line which shows the average of 0.972 BtNSA/60. When he has the puck behind the net, he assists on shots more than three times as often as the average forward in this sample. That is very, very good.

Sidney Crosby also shows up here, as does Joe Thornton. Fresh off recording his 1000th career assist a few nights ago, Thornton is considered one of the best playmakers in the league. Their ability to create offence in this way is merely one reason why they are both elite players.

While a Behind-the-Net Shot Assist is awarded to a player who completes this type of  pass, the next step is to see which players were frequently on the receiving end of these passes. But first, a bit of clarification. Since not all passes lead to shots, the following distinction is crucial: behind-the-net passes that lead directly to shots are different than behind-the-net passes that do not. The latter is not a Behind-the-Net Shot Assist because a shot was not taken after the pass was completed. Because we want to know who is taking these shots most often, we should not assume that these shooters are also the most frequent recipients of behind-the-net passes. It is important to know what the data is telling us before we analyze it.

Here is the leaderboard using the same sample as before, but this time we are measuring forwards by how often they shot the puck after receiving a behind-the-net pass:

Screenshot 2017-03-07 13.05.57.png

Nino Niederreiter shows up first here, taking a shot following a behind-the-net pass more than once every 30 minutes (2.159 times every 60 minutes) at 5v5; the average is 0.830 iBtN Shots/60. Niederreiter’s result is interesting itself, but more importantly, I believe, is that the previous leaderboard revealed that he is also one of the best passers from below the icing line. If you look at the first leaderboard again, you will see that Niederreiter shows up third overall, with 2.491 Behind-the-Net Shot Assists every 60 minutes at 5v5. This suggests that Niederreiter might have a subtle talent that is overlooked by the traditional hockey statistics. Further analysis of Niederreiter’s play below the icing line should be conducted to determine how and why he is so successful in both of these categories.

While Henrik Sedin led the way in terms of Behind-the-Net Shot Assists, his twin brother, Daniel, was the 6th most frequent shooter following a pass from below the icing line. I found this to be quite fascinating because their chemistry is undoubted by traditionalists and the analytics crowd alike, and this is yet another lens through which we can view it. Henrik is responsible for digging the puck out from below the icing line and then passing it in front, where Daniel is waiting to receive the pass and to shoot the puck towards the net. Playing below the icing line is one of the ways the Sedin twins create their magic.

Altogether, we can graph each player’s results in both metrics to visualize where their results rank in both areas.

Screenshot 2017-03-08 12.01.06.png

The x-axis measures the first metric in this post: Behind-the-Net Shot Assists. Players who appear to the right of the vertical green box are the best passers from below the icing line. Along the y-axis, you will find the most frequent shooters following a behind-the-net pass. The forwards who appear in the second leaderboard shown in this post are the ones who appear towards the top of this graph. The boundaries of both green boxes represent one standard deviation above/below the mean (i.e. the gray line) for their respective metrics. In the top right, you can find the players who are most involved in passing from behind the net and shooting the puck following these passes.

Two linemates on the Washington Capitals – Niklas Backstrom and Alex Ovechkin – are another interesting case study here. They spend most of their 5v5 ice time together, yet they appear on opposite ends of the graph. We can see that Backstrom is found in the bottom right, meaning he records Behind-the-Net Shot Assists quite frequently but is rarely the shooter, while Ovechkin is found in the upper left, indicating that he is the shooter more often than the passer. This passes (no pun intended) the eye-test because everyone knows that Ovechkin loves to shoot and is very good at it, too. Like the Sedins, I’d presume that Backstrom and Ovechkin work together to generate offence from below the icing line. Perhaps this is one reason why Ovechkin is arguably the best goal scorer of this era.

If you would like to see how the players on your favourite team perform in these metrics, you can do so here.

The ability to generate offence from behind the net has clear strategic advantages for teams who seek to be as offensively dynamic as possible. While entering the offensive zone with control of the puck is the best way to generate shots, teams with players like Nino Niederreiter or the Sedin twins in their lineup will probably create more shots following a dump and chase than teams without them. Sure, dump-ins are inferior to controlled entries, but players who can generate offence from “the office” or elsewhere below the icing line minimize the gap between both options.

Although I don’t suggest that coaches should preach the dump and chase, I assume that this strategy might be less risky if conducted with players who excel at generating offence below the icing line. In the future, we will eventually be able to pair this data with zone entry data to determine if this impact actually exists. Assuming that the impact is noticeable, I highly doubt that it will turn out to be a preferable option to controlled entries. At best, it is most likely the best option for an inferior strategy.

Of course, all of this theory assumes that playing below the icing line is a skill that can be repeated year after year. In other words, is a player’s BtNSA/60 a repeatable skill? From  the post linked at the beginning of this article, we know that BtNSA/60 is one of two components within a metric called Danger Zone Shot Assists. Compared to G60 (i.e. current scoring rate), Danger Zone Shot Assists per 60 minutes is a metric that is not only more repeatable, but is also a better predictor of future scoring than a players current scoring rate itself. A players Danger Zone Shot Assist rate is calculated by adding his Behind-the-Net Shot Assist rate with his Royal Road Shot Assist rate (i.e. how often he completes passes which travel across the slot prior to a shot being taken). While BtNSA/60 itself might not be an improvement upon existing metrics, it is definitely a core component of a statistic that improves our ability to predict a players future scoring rate.

Predicting future scoring is very difficult, especially in an era where goals are scarce and defences thrive. The data from the Passing Project is one resource that can help us discover new ways to repeatedly create offence — a mission that is now more important than ever before. The data shows us how players like Niederreiter and Backstrom break down these modern defensive systems by posing offensive threats whenever they have the puck below the icing line. Passing from this area is an avenue for success in the low-scoring environment that is today’s NHL. But for Gretzky, it was just another day at “the office.”


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