Contextual issues add a degree of uncertainty to statistical analysis. Quality of competition, quality of teammates, zone starts, and any number of other factors influence the ultimate performance of every player on the ice. These factors can sometimes make it difficult to tell who is contributing what to a team's efforts. Enter dCorsi.
dCorsi, or Delta Corsi, is a creation of Stephen Burtch now of sportsnet.ca. Essentially what it does is shows how well a player outperformed the Corsi data normally expected given his minutes. He explains it like this in the introduction post he wrote for NHLNumbers:
This dCorsi value represents the seasonal average level above or below Expected Corsi a player has produced for every 20 minutes of 5v5 game play in a given season when usage is taken into account.
You can find dCorsi values at War On Ice. If you look for them by hand you can find them under the Labs tab. Or, you can just click this link right here.
What's interesting when going through these numbers is how well Jason Demers fairs. According to dCorsi only Oliver Ekman-Larsson had a bigger impact on his team this season. A lot of the guys you would expect are near the top: Mark Giordano, P.K. Subban, Duncan Keith, Nick Leddy, and Dougie Hamilton among others. Demers is ahead of all of them though.
Among Stars defensemen Demers obviously led the way. Coming in behind him though was Jordie Benn. Jordie finished 17th in the league among defensemen. Former Dallas Star David Schlemko finished right behind him. This seems to invalidate the stat until you realize how good Schlemko has been with Calgary. Alex Goligoski and John Klingberg had solid seasons.
At the other end of the spectrum is Trevor Daley. His negative impact through dCorsi was equal to the positive impact of both Demers and Jordie combined. This data goes back to the 2006 season. Daley put up the worst dCorsi of any defenseman in the entire available data set. The only two players were were John Madden and Jay Pandolfo of the 2007 Devils.
The Stars biggest forward impacts belong to Colton Sceviour, Shawn Horcoff, and Brett Ritchie. They were in the mid-to-high 50's. The forward group is the most striking aspect of the entire exercise. The Stars forwards compare very poorly to the rest of the league. A big reason for that is that the players playing in defensive roles rated very poorly. Antoine Roussel, Cody Eakin, and Ryan Garbutt were three of the Stars four worst defensive forwards based on dCorsi Against (with Ales Hemsky).
Based on what we've seen here a reasonable strategy for making the biggest impact defensively on next year's Stars would be to improve the bottom pair by substituting one of the young defensemen for Daley (or fixing Daley), and finding some more capable defensive forwards to fill out the bottom six. When Jamie Benn, Tyler Seguin, Horcoff and Ritchie are your top defensive forwards there's a problem. That isn't intended to be a slight against them, but the group as a whole needs to be better.
They always say to end on a high though, so congrats to Jason Demers for the great season.