# Breaking down the components of Corsi over the first quarter of the 2015-16 NHL season

The NHL regular season is one quarter of its way through as Thanksgiving approaches south of the 49th parallel. The Montreal Canadiens and Dallas Stars have made early statements, Patrick Kane is inauspiciously atop the league’s points race and rookie phenom Connor McDavid was shelved long-term as he began to serve notice of his arrival.

The first 20 or so games typically paint a picture that will stay on display for the balance of the season. I wanted to examine how each NHL team has been performing to this point based on puck possession metrics. If puck possession truly has a strong correlation to playing winning hockey, then analyzing these season-to-date statistics should provide us a glimpse at the playoff picture. But anyone can look up Corsi and scan the list. Instead, I wanted to delve deeper into each puck possession component to understand how teams arrived at their current results.

The theory behind these statistics is that teams must be in possession of the puck in order to shoot on the net. Therefore, the more shots taken, and the fewer shots taken against you, are a strong indicator of how a player or team controls the game. Corsi statistics can be attributed to an individual player or an entire team. For my analysis, I have focused on team-only statistics. The metric is developed as follows:

Corsi For (CF) = Shots For + Missed Shots For + Blocked Shots For

Corsi Against (CA) = Shots Against + Missed Shots Against + Blocked Shots Against

CF % = CF ÷ (CF + CA)

Corsi is a situational statistic. If you think about it, how relevant is assessing puck possession of a player while he’s on the power play or shorthanded. It wouldn’t be valuable to dock a team for killing penalties when the opposition has a significantly higher likelihood of possessing the puck. Consequently, puck possession stats are often measured separately in scenarios such as 5-on-5.

I analyzed each team’s 5-on-5 Corsi For results initially. Since every team would have played a different amount of time at 5-on-5, I have equalized the season-to-date results based on a 60 minute game for my entire analysis. The charts below (split by conference) divide the shooting statistics by each component of Corsi: shots on target (simply referred to as ‘shots’), shots taken but missed, and shots taken but blocked. The teams are ranked from left to right based on who has the highest 5-on-5 Corsi For per 60 minutes.

This is the point where you all open up a new window to double-check the NHL standings, specifically that of the Metropolitan division, because you are certain that the Rangers were in first place and the Hurricanes were in last just the other day. No need to check; it’s still true. What this chart shows is how the Rangers succeed and the Hurricanes fail despite their puck possession figures.

Take a look at Carolina, for example. The Hurricanes have the most shot attempts for, but have the lowest shooting accuracy in the conference. Only 50.2% of their shot attempts result in official shots and they have by far the most combined missed and blocked shots in the East. On the other hand, the New York Rangers lead the conference with 57.2% of shot attempts counting as a shot.

Two of the Eastern Conference’s top squads so far in the 2015-16 season are the Montreal Canadiens and the Washington Capitals. Both these teams have proven to be strong puck possession teams. Unlike the Rangers and Hurricanes, Washington and Montreal have delivered median-level shooting accuracy. The difference is the quantity of shots by the Capitals and Canadiens that are on net. These are the only teams in the conference averaging north of 30 shots per game.

Next, I examined the same chart for the Western Conference. In comparison to the Eastern chart, the puck possession figures for the Western Conference are much more aligned with the current standings.

The two notable exceptions are the Anaheim Ducks and the Vancouver Canucks. Anaheim struggled out of the gate and the Stanley Cup hopefuls find themselves out of a playoff spot at the quarter-point of the season. Their puck possession results, however, are among the conference’s best and could provide hope that the season can still be resurrected.

The Canucks are in a similar position to the New York Rangers. In fact, Vancouver is leading the NHL in 5-on-5 shooting accuracy per 60 minutes. The Canucks reach the goalie or hit the twine in 58.6% of their attempts. Therefore, despite less shots taken compared to their Western peers, the Canucks remain in the hunt in the Pacific division.

The Central is as competitive in 2015-16 as any division has been in recent memory. At most, five teams will advance to the playoffs. Excluding the Avalanche, one of the other six franchises will be on the outside looking in. Based on the puck possession figures above, Minnesota will need to get more pucks on net to avoid being that team. The Wild are the only team at this point to have more than 50% of their shots taken result in misses or blocks.

But Corsi For is only one half of the equation. It’s time I started adding in the Corsi Against metrics. After all, you can take all the shots you want, but you’ll likely be outscored if you’re allowing the opposition to fire even more shots towards you. To illustrate, I have considered net shots, i.e., shots for, net of any shots against. This concept can be used for more than just shots. I also determined net shots missed and net shots blocked. If you have more shots than your opponent, your net shots will be positive. If the other team is the one with more shots, net shots will instead be negative.

The chart below summarizes net shots for the Eastern Conference. Again, I am only evaluating shots in 5-on-5 situations and results have been equalized over 60 minutes.

This chart will tell you one of two things: you will either be able to identify which teams control (and don’t control) the play or which teams have had above or below average goaltending in spite of their puck possession play.

The Capitals and Canadiens fall into the first group. Both teams have controlled the play by ensuring their shots are getting to the net while not sacrificing too many shots in their own direction. The Philadelphia Flyers are on the opposite end of the spectrum. The Flyers are among the top Corsi For teams in the Eastern Conference but are allowing so many more shots on net that their place has slid to the right side of the chart above and towards the bottom of the Metropolitan division.

The other factor was goaltending. In fact, the play of Cam Ward and Eddie Lack are key contributing factors as to why the Hurricanes have faltered despite limiting shots on their own net and solid Corsi For numbers. Craig Anderson and the Ottawa Senators are an example of where goaltending is helping a team withstand far more than an acceptable amount of shots against.

The similar chart for the Western Conference is included below. The St. Louis Blues were just north of median for Corsi For, but are top in the conference when considering net shots. The Blues are leading the West in shots on net and their net shooting statistics are attributable to their ability to divert the opposition’s opportunities.

Similar to St. Louis, San Jose’s new coach, Peter DeBoer, has the Sharks playing an improved puck possession game from the defensive side. The Sharks are 10th (out of 14) in the West in shots on net, but their ability to keep pucks away from Martin Jones has elevated their puck possession scores. Consequently, the Sharks are among the frontrunners in the Pacific.

The Arizona Coyotes have started the 2015-16 season with better than expected results after three consecutive years without a playoff appearance. However, based on the results shown above, I wonder how sustainable their start will be considering their unfavorable ratio of shots for and against.

Next, I took the net shots concept and added the other components of Corsi: net missed shots and net blocked shots. The charts below show each team’s progression to their current per 60 minute net 5-on-5 Corsi score at this point in the season. As before, I have segregated the results by Eastern and Western Conference.

I will use two examples to explain how to read this chart. First, let’s look at the Montreal Canadiens who currently have a +4.33 net 5-on-5 Corsi per 60 minutes. This figure can be broken down into pieces: +2.77 net shots (the blue bar), +0.60 net missed shots (the orange bar) and +0.96 net blocked shots (the gold bar). Montreal’s results were straight-forward compared to their Atlantic division rival, the Buffalo Sabres, because each Montreal component was positive. Buffalo, on the other hand, has a positive +1.87 net shots, but their net missed shots of -3.35 drops them below zero. Finally, Buffalo’s net blocked shots of +1.29 brings them back up to where they sit at a net Corsi of -0.19. Therefore, once you have followed the direction of each bar, the final placement of the gold bar will indicate the results of the net Corsi.

The purpose of this chart is to help visualize which components each team diverges from significantly compared to their opponents. The size of the bar relates to how much a team has either outpaced or fell behind their competition within that particular Corsi component. For example, Washington has clearly outshot their opposition in comparison to the large blue bar in the opposite direction for Florida – a sign that the Panthers are well outshot on most nights.

Buffalo’s large orange bar is proof that the Sabres miss fewer shots taken than their opponents. Oddly, that’s a bad thing in the puck possession world – even missed shots demonstrate a team is controlling the play. The Rangers have a significant sized gold bar which means they have fewer shots blocked than they block of the opposition. Again, this isn’t considered a positive result in Corsi calculations. In fact, it’s this questionable relationship among the variables that has many fancy stat purveyors preferring Fenwick, which is determined similarly to Corsi but without the blocked shots.

The similar chart shown below for the Western Conference highlights how dominant the puck possession numbers are for the Los Angeles Kings. The Kings not only have the NHL’s top net 5-on-5 Corsi per 60 minutes at +13.33, but each component is consistently well ahead of their opposition. Darryl Sutter’s squad controls the puck so much that they exceed a +4 in net shots on target, net shots missed and net shots blocked.

Unfortunately, the fans in Denver have witnessed the same level of consistency from their Avalanche. Colorado has a net Corsi of -13.47 with an enormous net blocked shots of -7.04. Colorado’s puck possession has been so poor that you can’t even wheel out the Corsi vs. Fenwick argument. Their net Fenwick is lower than any other Western Conference team’s net Corsi.

Puck possession out West is distributed more evenly than the Eastern Conference. In the Western Conference, 50% of the teams have a positive net Corsi. In the other conference only four teams (Carolina, Washington, Tampa Bay and Montreal) have a net Corsi above zero. Is this a derivative of puck possession coaching, a symbol of the Western Conference’s strength or a combination of both? The reason might not be clear, but the correlation between puck possession and results couldn’t be more evident in the West.

There remains approximately 60 more games on the schedule before postseason tickets are printed. Those teams with decent results, but below average Corsi, may see a drop off. And the opposite could hold true for those who have underachieved. By examining each component separately, you can begin to understand how puck possession highlights good and bad habits and how it translates into tangible results. After all, the big question remains whether improving your Corsi will increase your possession come June – possessing the Stanley Cup, that is.

Bob Sullivan writes periodically for SportingCharts.com and can be followed on Twitter at @mrbobsullivan.

NOTES

The puck possession data was obtained from war-on-ice.com on November 20, 2015.

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