Photo Credit: Sergei Belski/USA TODAY Sports
Since the dawn of hockey analytics, there has been a goal of summarizing the total value of an individual player’s contribution into a single number. The team at war-on-ice.com has made significant advancements in this area over the past year, culminating in the introduction of their Goals Against Replacement, or GAR, metric.
GAR incorporates most of the key quantitative metrics we know to be of value including, faceoffs, penalties drawn/taken, and various shot metrics in different game states in order to calculate how many goals a player’s efforts would contribute to a team versus a replacement level player. You can read more about the background of this stat in their blog here.
The team at War On Ice was nice enough to let me play around with the data, in the context of what we can expect from the 2015-16 Canucks. Let’s get into that after the jump.
My first question was how closely the GAR aligns with a team’s actual goal differential, the difference between the number of goals they score and the number of goals they let in. To do this, I summed the GAR for each team to create a team GAR, and plotted that against the teams actual goal differential for the last three full seasons (2011-12, 2013-14, 2014-15). As we can see, Team GAR was actually a pretty close fit with Team Goal Differential:
*Team GAR on the y axis, Team Goal Differential on the x axis
So the sum of the GAR for the various players on each team, actually aligned pretty closely with the team’s goal differential. So far so good. Next I looked at the relationship between Team GAR and Team Regular Season Points, which is key to securing a playoff spot:
*Team GAR on the x axis, Team Goal Differential on the y axis
As we’d expect, the alignment is slightly further apart from what we saw when comparing GAR and Goal Differential, but overall this is a pretty good fit. By comparison, here is 5v5 corsi close versus team points:
We’ve long espoused the importance of possession for a team’s success, but as we see, Team GAR looks to have a much stronger correlation to a a team’s wins. Interesting stuff.
Now that we’ve established that there’s a strong relationship between Team GAR and a Team’s Points, the next step is determining whether a player’s actual GAR can be predictive of their future GAR. To do this, I compared the player’s average GAR from the three preceding seasons (2011-12, 2012-13, 2013-14) to their actual 2014-15 GAR. Here are the results:
As the guys at War-On-Ice.com would tell you, GAR in its current form is a solid retrospective tool, but not yet what we hope it can be in the future in terms of predictiveness. In the future, we hope to see it incorporate things like playmaking ability and defending, to add further precision. That said, the predicted GAR in Table 4 above, based on the average from preceding seasons, was actually closer to actual GAR than I had expected.
At the very least, its a worthwhile metric to use when spit-balling on how the 2015-16 Canucks will do. In order to calculate 2015-16 Predicted GAR, I used the player’s 3 year average GAR, and calculated Predicted GAR using the equation in Table 4 above. Now to the results:
|Name||2012-13||2013-14||2014-15||3 yr Ave||Predicted GAR|
*Note: GAR data in table above varies from that currently available on waronice.com as the website has not yet been updated for end of season data.
Using this method to calculate Predicted GAR for the 2015-16 Canucks roster, as currently constructed, we estimate that the Canucks would have a Team GAR of 48.1, which would roughly equate to a 92 point season. Using the 3 year average GAR of 54.3, we would expect the Canucks to have a 93 points season. Using the data information that GAR gives us, we would expect that the Canucks will be on the outside of the playoff bubble next season.
During the course of the year, there has been a number of interesting developments in the analytics community, and GAR is definitely a stat to keep in mind when evaluating a team’s performance, and prospects for future success. By this measure, it would appear that we should expect the Canucks to slip outside of the playoff picture next year. What do you think?