When I started doing CSSI for the 2010-11 season, I did so with a general unease for some traditional NHL stats and a worry about the some shortcomings of the newer possession stats which have grown both more complex in their analytical uses and more accepted in casual hockey conversations since then. I knew that such stats were useful if used correctly, but I wondered if one could create an even better system through the best-possible method of hockey analysis: watching the game and reading the scoresheet.
After more than 250 games worth of using such a system on the Red Wings, I believe that what I've done is to create a good system which adds additional clarity to the current method, but not to an extreme degree. For the most part, CSSI has created an interesting index which coincides nicely with the expanded statistical analysis popular today, but still has many of the same shortfalls.
Looking at the system now, I'm not sure what's going to happen with it going forward. If I choose to continue doing it, things certainly won't be the same. Since CSSI has always been a two-part system (with goaltending considerations thrown in), I'll look at both systems separately. Today, we'll start with the points adjustments.
The CSSI Points System was designed to both better-identify the ways in which players made goals happen and to make sure points credit was properly distributed. The essential complaint against the current points system is that it only allows for credit of a goal, a primary assist, and a secondary assist. This would too often ignore the player who made an outlet pass to set up a two-pass scoring play or would too often give more credit to a guy for a tic-tac easy pass than it would for the guy camped at the net-front preventing the goalie from seeing the eventual shot.
At the end of the analysis, we can see that what CSSI points adjustments did was to inflate total points figures by about 40%. This is fine because, as always, the purpose of this system was never to use these figures to compare players across teams. Pavel Datsyuk's CSSI-adjusted points wouldn't tell us anything about how he stacked up to Jonathan Toews offensively, but it would give us insight as to how much of the Wings' point production he's really been driving.
The answer? Pavel Datsyuk has scored about 10.3% of the Red Wings' total points in the last three regular seasons; he's scored about 10.6% of their total adjusted points. This is actually one of the bigger percentage changes. The average difference in production is 0.1%. Tomas Holmstrom's differences account for the largest changes. His percentage difference between adjusted points and actual points was a whopping 0.8%.
In a certain way, It's good to see the numbers all hitting so close. The points adjustment system was designed to capture all the useful ways to help the Wings score, not to place differential values on each of those methods. A third assist is worth as much as a screener's assist. Unfortunately, I feel that this doesn't really tell us anything the eyeball test doesn't already.
If we were to ask "What did Tomas Holmstrom do for the Wings that directly led to scoring?" to somebody who has watched all of the same Red Wings games without the CSSI numbers, as long as that person isn't an idiot, I can say confidently that the answer would pretty well touch on the same things the CSSI numbers do. Holmstrom's screener's assist totals over the two seasons (23.5) tells us what the eye test narrative tells us. Niklas Kronwall's 30.5 third assists totals hint well at a puck-moving D-man with an outlet pass while Henrik Zetterberg's 16.5 self assists show us a guy who got defenses moving and Pavel Datsyuk's 18.5 bonus assists imply a magic puck-handler.
In this regard, the CSSI points adjustments have essentially worked as a prescription for the eye test. We know these things the players do because we watch, but the stats bring those things into focus. While I'm glad for the experience of having done points adjustments for the last three seasons, I don't think it's going to be worthwhile to continue this portion of analysis in the future.