ZONE TIME & GOALS

Recently, I mentioned the large player tracking project I conducted last season with regard to a post on Shot Generation. It attracted some attention and several questions were posed that spurred me to do a post on this. Instead of focusing on the individual players in the project, I’ll focus on the overall information and the details that people seem to be interested in.

A quick explanation of the project: All even strength goals and assists for 72 forwards in the NHL were tracked to capture various information about scoring. The project included goals from the regular season and playoffs spanning from the 2012-13 season through the 2014-15 season. Ultimately, there were 7142 goals that were used to create this data. Some of the goals that were originally tracked (over 8000) were thrown out for various reasons such as goals scored a few seconds after a power play ended, goals on empty nets or with an extra attacker, etc. These are usually listed as even strength goals for NHL purposes, but the information collected would not have been technically even strength and thus was excluded. The players included in the study originated from every team in the league and are listed near the end of this post. Further, I had a lot of help doing this project from some amazing volunteers whom I have listed at the end as well. Thanks to their selfless efforts, a project of this scale was able to be carried out. Continue reading

“Watch the Game, Nerds!”

Hockey has long been a sport in which hard work is cherished as the ultimate virtue. You certainly won’t find me arguing that players and coaches do not need to work hard, but somewhere along the line, an undercurrent of distaste for intelligence has developed. Using analytical tools to evaluate players and teams has been met with suspicion and often even hostile disapproval.

Don’t get me wrong, I’m not talking about all intelligence being frowned upon here, just the kind that comes from the mouths of those that have never played the game at the NHL level. Intelligent analysis or strategy from “hockey guys” is of course granted a place of almost mythical honor in the sport, so I don’t think it’s fair to say that hockey rejects smartness as a whole. It’s more that hockey often demands that you have the appropriate level of street cred, or rink cred, I guess, in order to be considered to have intelligence of any actual value.

The heart of the now years long stats vs anti-stats battle lies in this mentality. Traditional analysis in hockey tends to put the most stock in experience and knowledge gained from years of playing the game. Statistical analysis in hockey tends to put the most stock in the gathering of data and analysis based there upon. “Watch the game, nerds” and “Your eye-test sucks” spring from the perceived disconnect between those two sides.

Traditional analysts see statistical analysts basing opinions of a player’s skill or value on numbers and perceive a lack of “hockey knowledge” in the results of a computation. This hockey knowledge has in many cases been built through playing the game at an elite level or being part of the game for many years. No one wants to feel like their hard earned skills are not unique or special and are easily replaced by a nerd behind a computer who didn’t have enough talent to play the game. What they usually mean when they say “Watch the Game, Nerds” is “Watch the game the way my years of experience tell me to watch it. Value the qualities that I value.” Continue reading

Back To Basics: Offensive Zone Entries

When I first got into writing about hockey, I did some primers on stats to help people learn. I haven’t done much of that in the past year and recently some hockey people asked if I would be willing to do some more, so basically it’s their fault if you don’t like this.

If you are newer to the statistics side of hockey, you may not know what all the fuss is about with regard to zone entries. Analysts on TV will often preach about the virtues of “getting the puck deep” during games, but on your favorite hockey sites or Twitter, you’ll see analysts yelling about carrying the puck into the zone. Who’s right? Which way is better?

Dumping the puck into the offensive zone is a common tactic when teams are trying to get a line change done, so these are not usually tracked by analysts interested in zone entries. The team dumping the puck in is not giving chase, save for perhaps one forward and that is simply to buy time for the line change to get done.

When teams are on the offensive attack, they have several options for getting the puck into the offensive zone.

Controlled Zone Entries:

Carry Ins: The puck is carried into the offensive zone and control of the puck is maintained well past the blue line.

Passes: The puck is passed from one player to another as the attacking team enters the offensive zone with control of the puck maintained well past the blue line.

Uncontrolled Zone Entries: 

Dump & Chase: The puck is shot into the offensive zone, often by a defenseman, and the attacking team goes on the forecheck to get possession of the puck.

Chip & Chase: The puck is angled off the boards or chipped around the player defending against the entry with the attacking players hot in pursuit. The puck does not go all the way to the end boards, but instead is like an indirect pass to another attacking player or the player who chipped it in the first place.

Turnover Entries:

The defending team retreats into their own defensive zone with the puck usually to buy some time and set up an offensive attack through a regroup or controlled breakout. After bringing the puck back into their own defensive zone, a player from the other team forces a turnover or intercepts a pass thereby gaining possession of the puck in their offensive zone.

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My “Nontraditional” Path To Hockey

Growing up in rural Northwest Indiana (about 45 minutes outside of Chicago), we didn’t have cable TV. Basketball, baseball and football were the staple sports in my family. My dad coached basketball and tried his best to make me a much better player than I really was. I watched or listened to Cubs games with each of my grandfathers. Every Sunday was devoted to watching Bears games. I’ve played a lot of sports throughout my life, but focused mainly on equestrian sports for a long time.

Hockey was not a very big part of my life then. Blackhawks games were not on regular TV stations so casual viewership wasn’t really an option. Even in high school in the early 90’s, I was little more than a casual fan of hockey. It wasn’t until 2008 that I really started devoting any of my time to regularly watching hockey. In February of 2013, I joined Twitter because there was a contest to win Blackhawks game tickets on CSN Chicago. I know that seems hilarious, but it’s the awful truth. I quickly found there were lots of people like me who followed hockey on Twitter and started trying to figure out where I fit in that community.

Over the summer between the 2012-13 and 2013-14 seasons, I started learning about “fancy stats” as they were so often called then. I thought it was a cool way to gain more understanding of the game I had come to love. In late November of 2013, I had a bunch of thoughts in my head about hockey that were too long for Twitter so I created a blog on WordPress. I was just going to post that one thing and be done with it. The post was about Brandon Pirri and Chicago’s longstanding search for a 2nd line center, in which I gave Pirri the “fancy stats” treatment. I really thought only 3 or 4 people would read it, we’d discuss it on Twitter a little bit and that would be the end of it. As with so many things in life, it didn’t really end up that way. Continue reading

Puck Possession, A Potentially Misleading Principle

Over the years, analytics in hockey have grown and evolved. Shot metrics and measures that provide context to them have become part of the standard toolbox used by many inside and outside of NHL offices. The principle of puck possession, while known to the hockey world since time immemorial, has taken on a whole new level of importance with shot metrics gaining in popularity.

Shot metrics were initially* explored in an effort to discover a decent proxy for time of possession in hockey. Much like you see in other sports such as football, people wanted to get a better handle on quantifying how often and for how long specific teams had the puck as opposed to playing defense, i.e. time of possession. The thought process here was fairly logical. Because the objective in hockey is to score goals, having the puck is better than not having it.

Shot metrics, such as Shots On Goal, Shot Attempts (Missed, Blocked, On Goal) and Unblocked Shot Attempts (Missed, On Goal), were explored as ways to potentially find measures that could reproduce time of possession without necessitating a person with a stop watch timing every possession in every NHL game. As it happened, a strong correlation was found between those metrics, particularly Unblocked Shot Attempts, over the course of the regular season, and success, namely landing a spot in postseason play. That correlation provided confidence in the reasonable reliance on these metrics as tools to measure the strength of teams.

Teams which show well in these metrics are often called “strong possession” teams. “Puck possession” has become a commonly used term and is the generally accepted phrase for the modern approach to achieving success in hockey. “Puck possession” is a bit of a misnomer though in its current usage.

Teams spending long periods of time in the offensive zone, or possessing the puck, is good right? Not necessarily. It’s certainly better than constantly being hemmed into the defensive zone, of course; however, simply having the puck in the offensive zone (passing, running the cycle, i.e. what many term as “puck possession”) is not what has been established as having a high correlation to success. Shot generation (creating shots toward the net) and shot suppression (preventing shots toward the net) are actually the metrics that have been linked to success.

Regardless of how long teams spend in the offensive zone, if they are passing and failing to generate shots, they are not exhibiting the hallmarks of success because they are not generating shots toward the net. If you try to visualize this, these long periods of possession often resemble a power play. The attacking team gains the offensive zone, establishes a cycle and passes the puck numerous times looking for a “perfect shot” instead of creating multiple shot attempts during the possession.

The common thinking that may be leading some teams to this is that a shot toward the net creates the opportunity not only for a goal, but for a rebound or miss that could be collected by the defending team and thus necessitate getting back on defense themselves. It may be that some coaches feel long periods of possession, despite a lack of shot generation, are a form of shot suppression or at the very least, in keeping with the principle of puck possession. Technically, this is true; however, the teams using this form of possession often seem to be lacking in solid defensive systems.

Shot suppression is not achieved simply by keeping the puck out of your defensive zone by holding it in the offensive zone. Every team in existence has to get back on defense. Denying the attacking team’s entry to the offensive zone, aggressive backchecking, sound and well executed breakout plans from the defensive zone and the like are far more effective in achieving shot suppression than trying to keep the puck in the offensive zone for extended periods of time. These strategies are also more effective for shot generation because they are all ways to help the team get back on the offensive attack using a quick transition.

It is intriguing to think that the quest for a good proxy for time of possession has actually led to a finding that success is not really a matter of time of possession, but a matter of shot generation and suppression, which are far more complex than simply being in the right zone of the ice.

Teams like the Colorado Avalanche seem to understand the long held tenet of “puck possession”, but have attempted to adhere to that principle using the possession time strategy as opposed to the shot generation/suppression strategy. The Avalanche are not the only example of this in the NHL to be certain. It probably isn’t a coincidence that they use systems which, on their surface, seem in keeping with the principle of puck possession, but which, upon closer inspection, display a failure to grasp the true meaning of the principle.

As the decision-makers are afforded a more informed, nuanced approach to the principle of puck possession through the adoption of shot based analytics, it will be interesting to see the changes made to their strategies for adhering to that principle.

*Shot metrics were explored for several reasons initially, not simply for time of possession. Work was done to see what meaning shot metrics and scoring chances had within the game of hockey by bloggers in the Edmonton Oilers fan base after learning that the team tracked scoring chances. Thanks to Garret Hohl for mentioning this to me so I could edit and include this for the sake of accuracy.

Competitive Advantage: Putting 2 and 2 Together

With expansion plans in the works, the NHL and the teams that comprise it are under pressure to increase revenue. Sports are entertainment and in the entertainment business, fun is money. It’s not rocket science to link a rise in the number of fans to a rise in the amount of money coming in. Every team in the NHL wants to win. Even the teams that have been rumored to have tanked for attractive draft picks want to win, albeit just a little bit farther in the future. All things considered, winning, or even the hope of winning, is good for the bottom line.

Hockey teams are businesses comprised of human beings. Most human beings, like it or not, allow their feelings about a person to dictate how much latitude and gratitude they are willing to give. If a player is well liked, works hard and listens to the coach, the coach will often like that player. That player will get more latitude for the mistakes he makes and more gratitude when he does something well.

The coach’s feelings about a player will often direct his eye away from the player’s deficiencies and toward his strengths. This works the opposite way as well. If the coach is not very fond of a player for whatever reason (preconceived ideas of the player’s skill level, work ethic, personality, etc…), he is more likely to see that player’s mistakes or shortcomings than his talents. This is often referred to as “confirmation bias” and it is just basic human nature inside and outside of sports.

The problem with this part of human nature is that it leads to decisions based on skewed information. Looking at this through the lens of hockey as a business, this can have a negative impact on the bottom line. The business of sports is about gaining a competitive advantage and confirmation bias often hinders this. Gaining a competitive advantage when management and coaching are not on the same page can be a monumental chore.

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Clearing the Defensive Zone: The Dangers of Dumping the Puck Out

Over the course of the season, I and others have often talked about the importance of defensive zone exits. On numerous occasions, we have debated (on Twitter) the pros and cons of simply getting the puck out of the zone to relieve offensive pressure versus starting a proper breakout play. People often argue that because players are tired at the end of a shift, particularly one where they have been actively defending for an extended period, simply getting the puck out of the zone without icing helps the team.

Ways the puck leaves the defensive zone:

  • Happenstance: a pass from one offensive player to another misses and the puck ends up in the neutral zone causing the attacking team to regroup and restart their attack;
  • Controlled Exit:
    • Carry Out: One of the defending players gains control of the puck and skates it across the blue line;
    • Exit Pass: One of the defending players gains control of the puck and makes a tape to tape pass to a teammate in the neutral zone;
  • Uncontrolled Exit:
    • Dump Out: One of the defending players gains control of the puck and shoots it into the neutral zone:
      • Missing the intended target;
      • Without an intended target, i.e. simply to get the puck out of the defensive zone;
      • To execute a line change.

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Zone Entries: CHI vs NSH Player Breakdown

Now that the team breakdown is complete, we can move on to the player breakdown of the zone entries throughout the Chicago versus Nashville playoff series. Aside from telling you how each of the players fared during the series, I also want to show you some of the possibilities for using the information tracked through microstats (such as zone entries and exits) to evaluate players, line combinations and systems.

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The “End All Be All”

Recently, I expressed my frustration with the lack of advanced stats being discussed in a meaningful way by many analysts on TV broadcasts of NHL games. My main point in expressing that frustration was to point out that many hockey fans are not on social media and often do not have access to or knowledge of the resources available to explain stats they may not be familiar with. I was advocating for the inclusion of these stats in broadcasts so that people who are unfamiliar with them could feel more comfortable with them and get some exposure to them in an accessible setting. This level of comfort would decrease the pro-stats versus anti-stats strife and be better for everyone in my opinion. Unfortunately, some read this as me trying to put down people who are not on social media or who aren’t into stats, which was not at all my point. Perhaps I could have done a better job making that clearer but apparently I fell short in that regard.  

I received many and varied responses to that post but one of the best basically said that when more NHL teams admit to using them, fans and media would begin to feel more comfortable accepting advanced stats as a useful tool. With that said, I was intrigued this past week by new information regarding the use of advanced stats by some NHL teams. While many in the “advanced stats crowd” have known for a while that there are several teams in the NHL that use their analytics budget for more than just tracking hits, information came out this week that expanded upon that and more importantly, the information was publicized by NHL.com thereby reaching a far larger audience.

While doing interviews with the coaches and players of the San Jose Sharks and L.A. Kings, NHL.com writer Corey Masisak (on Twitter @cmasisak22) asked questions about puck possession and the teams’ use of stats. He was met with a fairly frank discussion that led to confirmation from both teams that they do in fact track puck possession data and use it in their strategies, player usage, etc.

During media availability for the Chicago Blackhawks and St. Louis Blues series, Blues head coach Ken Hitchcock admitted that both he and Blackhawks head coach Joel Quenneville use advanced stats for their teams. On a much smaller level, I was able to get information from a woman who knows one of the Blackhawks analytics people regarding the team’s use of advanced stats. She informed me that the Blackhawks internally track Corsi, Fenwick, zone entries and exits, among other data. This information is then presented to the coaching staff for their use.  Obviously, my Twitter feed is a drop of water compared to the ocean that is the reach of NHL.com and the many other media sites and publications covering the NHL, so I do not expect that to have anywhere near the impact of the aforementioned information.

Regardless, this advanced stats usage by NHL teams such as the Sharks, Kings, Blues and Blackhawks being mentioned and explored by major media sources is a big deal. It is very intriguing. I write about and tweet about advanced stats regularly and sometimes meet with resistance to the information I disseminate. I wondered if perhaps seeing that these very successful teams use advanced stats would sway the opinions of those who had been skeptical as to their usefulness. I took to Twitter and asked for thoughts on the matter. I also made sure to explain that I was not trying to insult or make fun of anyone in order to encourage more honest responses. Obviously my audience, for the most part, are pretty accepting of advanced stats but some of them are not.

The majority of the responses I received from the skeptics boil down to this:

Numbers and stats are fine but they are not the “end all be all” of hockey analysis. You cannot just rely upon numbers to decide who the good players are. The eye test has to agree for the stats to mean anything.

Obviously, I am paraphrasing and summarizing here because several people really took the time to lay out their thoughts and, I would like to add, the majority who responded did it in a very respectful and congenial manner.

The “End All Be All” was the most widely mentioned criticism of advanced stats in the tweets and emails that I received. There seems to be a wide spread notion that folks in the advanced stats crowd begin and end all analysis with the numbers. Perhaps it comes across this way because there just are not that many people in each team’s fan base, at least for the American teams, that focus on this information. Being one of the very few who do stats analysis for a team may lead people to think that stats are the only thing that particular person looks at when in fact it is simply the lack of that type of information from other sources making it stand out.

For the past year, I have followed along on Twitter and frequented the websites and blogs of as many advanced stats people as possible. That is a very short time and happens to coincide with the amount of time I have been on Twitter. In that short time, I have learned an amazing amount from people who have revolutionized stats in hockey and people who use stats as part of their analysis of the teams and players. In that year of paying close attention to and having frequent discussions with these people, not once have I ever heard even one of them say that advanced stats are the end all be all in analyzing hockey. Never.

I think the “end all be all” argument against stats is more a function of perception than reality. Often the advanced stats pack provides a counterargument to more “traditional” analysis by citing ways that the numbers show a different reality than what is being alleged. If the majority of what you have heard in the way of hockey analysis is not numbers related and then it is attacked based upon numbers, it makes sense that you may develop an aversion to the numbers. Again though, I have never heard any in the advanced stats crowd say that numbers are the only way.

I know of several hockey sites that do a wonderful job of breaking down plays and strategies. They are not all that plentiful so people have to search them out. Hockey is so often presented as hit, shoot, score that the actual strategy to the game is left by the wayside fairly often. Further, there are people who are doing tracking projects for zone entries, zone exits and passing. These manual tracking projects require a lot of time to carry out and frankly, I do not think it will shock anyone to learn that not every NHL team has a member of the public that does this.

The long and short of it is this: Hockey is a tough game to analyze. It is more fluid than many other sports and lacks the technological applications that some other sports have to help track data. Even the data provided to the NHL is tracked by people, so as fans we have to make do with what we have. No, Corsi and Fenwick are not perfect, but they are the best tools we have at this point to analyze puck possession and puck possession is the name of the game. All told, I think that the more people are hearing about teams using advanced stats, the more they are coming to accept that they are useful, but they still have some reservations.