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Plus/Minus: Adjusting For Goaltending

Plus/minus can be an extremely misleading statistic in a lot of ways.  One of the things it includes some results from special teams - a player on the ice for a shorthanded goal for gets a plus, and a player on the ice for a shorthanded goal against gets a minus.  Additionally, the NHL doesn't filter out empty-net situations, and that further adds to the noise.

There are other factors that should be adjusted for as well; more on that after the jump.

Before we get into adjusting plus/minus, let's remove those factors (special teams, empty net goals) that we discussed above.  Fortunately for us, Vic Ferrari's Time On Ice program does it for us.  Here then are the Oilers plus/minus results at even-strength with empty-net goals excluded:

Forwards

  • Dustin Penner: +44/-29 (+15)
  • Shawn Horcoff: +47/-38 (+9)
  • Ales Hemsky: +43/-37 (+6)
  • Robert Nilsson: +35/-30 (+5)
  • Sam Gagner: +42/-38 (+4)
  • Ales Kotalik: +15/-13 (+2)
  • Marc Pouliot: +26/-26 (EV)
  • Andrew Cogliano: +37/-38 (-1)
  • Kyle Brodziak: +29/-31 (-2)
  • Fernando Pisani: +19/-22 (-3)
  • Ethan Moreau: +34/-38 (-4)
  • Zach Stortini: +16/-20 (-4)
  • Liam Reddox: +16/-22 (-6)
  • Patrick O'Sullivan: +8/-15 (-7)

Defensemen

  • Denis Grebeshkov: +61/-48 (+13)
  • Lubomir Visnovsky: +37/-26 (+11)
  • Sheldon Souray: +49/-44 (+5)
  • Tom Gilbert: +62/-58 (+4)
  • Jason Strudwick: +25/-30 (-5)
  • Ladislav Smid: +29/-35 (-6)
  • Steve Staios: +41/-49 (-8)

One of the first adjustments that we can make is on the minus side of the equation.  Vic Ferrari has proved that individual players have basically no impact on the save percentage of the goalie behind them, so we should filter out the variance in the goaltending behind each of these players.  As a bonus, this will help eliminate the effect that different opposition has on players; one of the big advantages to playing against say, Chris Thorburn instead of Ilya Kovalchuk is not just that Kovalchuk is more likely to get a shot, but he's also more likely to score on a shot he does take.

Individual Oilers had ave percentages behind them that ranged from .895 to .936; the team average was .925.  Here's what those plus/minuses look like with everybody's even-strength save percentage adjusted to the team average:

Forwards

  • Dustin Penner: +44/-32 (+12)
  • Shawn Horcoff: +47/-40 (+7)
  • Ales Hemsky: +43/-37 (+6)
  • Robert Nilsson: +35/-31 (+4)
  • Sam Gagner: +42/-39 (+3)
  • Zach Stortini: +16/-14 (+2)
  • Ales Kotalik: +15/-13 (+2)
  • Marc Pouliot: +26/-26 (EV)
  • Andrew Cogliano: +37/-38 (-1)
  • Kyle Brodziak: +29/-30 (-1)
  • Liam Reddox: +16/-17 (-1)
  • Fernando Pisani: +19/-22 (-3)
  • Patrick O'Sullivan: +8/-13 (-5)
  • Ethan Moreau: +34/-41 (-7)

Defensemen

  • Denis Grebeshkov: +61/-44 (+17)
  • Tom Gilbert: +62/-52 (+10)
  • Lubomir Visnovsky: +37/-31 (+6)
  • Sheldon Souray: +49/-52 (-3)
  • Ladislav Smid: +29/-23 (-3)
  • Jason Strudwick: +25/-33 (-8)
  • Steve Staios: +41/-52 (-11)

Some big movers here.  Denis Grebeshkov has clearly had an outstanding season, and Tom Gilbert was getting killed by the save percentage behind him and looks much better here.  On the other end of things, it seems fairly clear that Steve Staios and Jason Strudwick were the biggest problems on the blueline.

Up front, Dustin Penner remains the best forward by this measure, but not by the rather incredible mark he posted without the adjustment.  Stortini and Reddox look much better, while Ethan Moreau sinks to the bottom of the pack up front.

Up next: adjusting for on-ice shooting percentage.