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The Trotz Philosophy: Shot Quality Over Shot Quantity

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Some players are having an easier time than others getting to the areas on the ice that lead to higher quality chances.

Columbus Blue Jackets v New York Islanders Photo by Bruce Bennett/Getty Images

As Barry Trotz continues to make his mark for the 13-9-3 Islanders, shot quality has been the running theme of the season. The idea is fairly simple - pass up lower danger shots to try and generate better opportunities to score. A lot of times that is easier said than done, but the Islanders seem to have - at least through 25 games - figured out some of the answers.

At a high level for the season, the Islanders rank 26th in Score-Venue Adjusted Shot Attempt Share (more popularly known as Corsi For) at 46.78% in 5-on-5 play. They rank 20th in High Danger Chance share at 48.59%. These are not great results, but the positive differential between their high danger percentage and overall attempt share percentage does indicate that they are generating a higher amount of quality opportunities than expected per attempt they take. In other words, they are practicing what they are preaching.

Over the last 10 games, the numbers are better for the Islanders. Even without Casey Cizikas, Matt Martin, and Andrew Ladd for much of the latest subset of games, the Islanders rank 19th in overall attempt share at 49.85% Score-Venue Adjusted. They rank 15th on high danger chances at 50.76% as well, which is marked improvement over their overall season performance. Below we can see the overall rolling 10 game average for the season for all attempt types, clearly indicating tangible improvements in performance as the season has progressed.

Data Through December 3

Let’s dig a bit deeper though. We know the coaching staff is accentuating the need for quality shots. However, what we can’t see in the above data are how individual players are performing themselves. The below visualization depicts some interesting findings.

Data Through December 3

Because this is looking at things solely from a team-relative perspective, we are using “relative” metrics on both axes. Essentially, what this does is normalizes all of the shot attempt data while a player is on the ice versus when they are on the bench. A Shot Attempt% Rel of 0 indicates the Islanders are no better or worse when that player is on the ice. A Shot Attempt% Rel of 2.50 would indicate the Islanders are getting 2.5% more shot attempts than their opponents, relative to the team’s average, while that player is on the ice. This works for high danger chances too, as well as any other type of attempt (shots on net, unblocked, scoring chances etc.).

From a technical perspective, a few things to call out. There is a high correlation between overall shot attempts and high danger attempts. Additionally, the data also appears to be pretty predictable given the high r-squared of 0.60. The data is also statistically significant, as the p-value is below 0.0001.

Furthermore, if we look at the diagonal trend line, we can discern a few things. The trend line itself sets expectations for future performance. In English, this means that for every coordinate on the shot attempt relative side, there is a coordinate on the high danger side that creates an expected value. You can use the following slope formula to get those expectations:

HDCF Rel = 1.212* CF%Rel + -0.105645

As an example for application purposes, if a player had a CF% Rel of +1.00, by plugging that into our formula, we could expect the high danger relative number to be +1.106%.

To bring this back to our chart, any player who is “above” the line (i.e. to the left of the line) has higher high danger relative percentages than their expectation (which we’d find using the formula). Any player below the line has percentages worse than their expectation.

Some key takeways? Anders Lee and Johnny Boychuk are performing well above their expectation. This means when they are on the ice, the Islanders are getting more quality shot attempts per overall attempt than any other player on the team. The player performing the worst? Jordan Eberle. When Eberle is on the ice, the Islanders are getting 4.78% more overall attempts than their opponents, but their opponents are actually getting 2.47% more high danger chances than the Islanders. That’s a huge difference and something worth monitoring as the season progresses. Below I’ve listed the overall differentials:

Data Through December 3

Now that we are over a quarter into the season, some clear findings are starting to take shape. How this ultimately parlays into the long-term strategy of Barry Trotz and Lou Lamoriello remain to be seen, but that doesn’t change the two main takeaways of this research:

  • The more shot attempts you are on the ice for, the more likely it is you will be on the ice for more high danger chances
  • There are some players who have not to the trend, both from a positive and negative perspective, which could be used in future strategy and roster construction discussions.

This has all been a major contribution to the Isles’ solid start to the season. And perhaps, it is the catalyst for success during the Trotz era.

All data is from Natural Stat Trick