Friday, July 25, 2008

Top 20 Adjusted +/- Ratings (Counting Stat)

In my sabermetrics and hockey posts this summer, I have been discussing +/- ratings. I have shown one way to compare +/- ratings on different teams using on and off ice performance and given the top 20 and worst 20 ratings by that method. I have also shown another method which treats +/- as a counting stat (total values over a season are important) instead of a rate stat (per minute values are important). There are also normalized to teams in different manners. This will lead to some discrepancies between the lists of top and worst players. It is useful to look at different problems in different ways. Different insight is gathered by doing this. The biggest difference between rating systems is that the counting stat includes more defenceman (who in general play more minutes and in more varied circumstance than forwards and thus get lost in a rate stat).

The first step to calculating adjusted +/- ratings as a counting stat is to determine the team values, which are essentially the zero point for a player on a given team. Here they are:

Team +/- Rating Adjustments 2007/08
Team+/- adjustment
Anaheim Ducks+4.4
Atlanta Thrashers-7.0
Boston Bruins+1.4
Buffalo Sabres+1.6
Calgary Flames+2.8
Carolina Hurricanes+0.4
Chicago Blackhawks+2.8
Colorado Avalanche+3.2
Columbus Blue Jackets-2.0
Dallas Stars+3.8
Detroit Red Wings+9.8
Edmonton Oilers-5.8
Florida Panthers-0.4
Los Angeles Kings-6.6
Minnesota Wild-1.2
Montreal Canadiens+2.4
Nashville Predators+0.2
New Jersey Devils+1.6
New York Islanders-6.2
New York Rangers+1.4
Ottawa Senators+5.6
Philadelphia Flyers-0.2
Phoenix Coyotes-3.0
Pittsburgh Penguins+3.8
St Louis Blues-4.2
San Jose Sharks+0.6
Tampa Bay Lightning-9.6
Toronto Maple Leafs-2.6
Vancouver Canucks+0.2
Washington Capitals+2.8


Most teams are not too far off from zero. There are some exceptions at both ends. The Detroit Red Wings lead the way at +9.8, followed by the Ottawa Senators at +5.6 and the Anaheim Ducks at +4.4. At the bottom of the pack is the Tampa Bay Lightning at -9.6, followed by the Atlanta Thrashers at -7.0 and the Los Angeles Kings at -6.6. Team +/- adjustments depend upon how the team did at even strength and thus power play success as in the Montreal Canadiens or shootout success as in the Edmonton Oilers is not included.

Using these team adjustments as a baseline here are the top 20 adjusted +/- ratings last season along side their ranking in the on/off ice adjustment. For the most part the same players are highlighted. Only players who played 50 or more games with one team are included.

Top 20 Adjusted +/- Ratings 2007/08
RankPlayerTeamAdjusted +/- On/Off Ice Rank
1Pavel DatsyukDet+31.25
2Nicklas LidstromDet+30.217
3Ryan GetzlafAna+27.67
4Dany HeatleyOtt+27.42
5Duncan KeithChi+27.257
6Johnny OduyaNJ+25.415
7Alexander OvechkinWas+25.216
7Viktor KozlovWas+25.23
9Jarome IginlaCal+24.28
10Jan HejdaCBJ+22.030
11Jassen CullimoreFlo+21.440
12Michel OuelletTB+20.64
13Jason SpezzaOtt+20.412
14Henrik ZetterbergDet+20.213
14Patrick SharpChi+20.281
14David PerronStL+20.21
17Mats SundinTor+19.619
18Douglas MurraySJ+19.422
19Jason ArnottNas+19.29
19Brendan MorrowDal+19.227


The lists are clearly not the same, but they tend to highlight the same players. Which list is better? It depends what you are looking for. If you want to know total +/- contributions this one is. If you are interested in per minute stats the other one is.

Pavel Datsyuk climbs a few points to lead this list. He is followed by teammate Nicklas Lidstrom. Defencemen do better on this list because they tend to have more playing time and thus will have higher ranks in total +/- than in per minute ones. Ryan Getzlaf and Dany Heatley are next. They did well on both lists. Duncan Keith comes fifth. He is the first new name. He fell significantly on the per minute list because of high ice time and because his teammates did well when he was off the ice (better than teammates of Ryan Getzlaf or Jarome Iginla for example despite being on a weaker team). Next up came Johnny Oduya and the Washington pair of Alexander Ovechkin and Viktor Kozlov and then Jarome Iginla. All are players who rank well on both rankings. In tenth and eleventh are Jan Hejda and Jassen Cullimore. They are two solid stay at home defencemen who missed out on the other top 20. Michel Ouellet drops to 13th due to decreased ice time. Next up are Jason Spezza, Henrik Zetterberg Patrick Sharp and David Perron. Spezza and Zetterberg are ranked approximately the same on both lists. Sharp climbs significantly to make this list. Perron drops from number one on the other list due to low ice time. Mats Sundin is next with approximately the same rank. Douglas Murray is another defenceman who climbs into the list. The list is rounded out by Jason Arnott and Brendan Morrow (who did not make the previous list). This is another group of players who overlap with the other list. The main difference is more defencemen make this one because they get better +/- ratings with increased ice time. There is an anomaly with Chicago Blackhawk players as they are ranked far lower on the on/off ice list than they are here. That deserves further discussion and will be saved for another day.

Missing from the previous list are Paul Stastny, Joe Thornton, Milan Michalek, Sidney Crosby, Shawn Horcoff and David Booth. All finish well in the pluses on both lists. Booth and Horcoff slip the furthest due to low playing time.

Adjusting +/- ratings in this manner as a counting stat is a useful way to pick out the best players in the NHL. It does a better job of highlighting defencemen who played well than the other method. It does not rate players who played very well, but in limited roles, as highly. For the most part, it highlights the same players as the other system.

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