The Plus/Minus rating is a statistic
that attempts to determine a player’s combined offensive and defensive contribution to his team. The higher the rating, the better.
How is it calculated?
Whenever a goal is scored in any situation except on a power play, all the players on the ice for the scoring team receive a “plus” (their ratings are increased by one), and all the players on the ice for the team that is scored against receive a “minus” (their ratings are decreased by one). The idea is that the players on the ice have contributed in some way to the score either for or against them. Plus/minus is not tallied for goalies. Goalies have enough statistics of their own to be concerned about.
Curiously, a player who is credited with an assist on a goal may not still be on the ice when the goal is scored to have his plus/minus rating changed. Player substitution happens on the fly in hockey. A player can advance to the center red line, dump the puck deep into the other team’s zone, and return to the bench. Meanwhile, if another player on his team reaches the puck before a defending player does, and passes it to a player who scores a goal, the player on the bench will be credited with an assist but will not see a change in his plus/minus rating for the goal. This is because assists are based on puck possession, but plus/minus is not.
The statistic has been tallied since the 1967-68 season, or since the National Hockey League expanded from the Original Six to twelve teams. Obviously it means another duty for the official scorers who attend every game.
Since 1982-83, an award has been presented to the player (or players) with the best plus/minus rating at the end of the year, having played a minimum of 60 games, which is roughly three-quarters of the season. The sponsorship of this award has changed a few times in the last twenty years. Traditionally, $5,000 is donated on the player’s behalf to a charity of his choice.
Bobby Orr’s rating of +124 in 1970-71 is often cited as one of the NHL records that will never be broken. Amazingly, it was very closely approached six years later when Larry Robinson achieved a plus/minus of +120. Robinson also holds the record for the best career plus/minus with +730. Since 1987, when Wayne Gretzky led with +70, no one has led the league with even half Bobby Orr’s record total. The forgettable Bill Mikkelson holds the record for worst plus/minus in a season with -82, when he played for the 1974-75 Washington Capitals. That was the Capitals’ inaugural year and the team was horrible.
How is it useful?
I would say that it isn’t terribly. Part of beauty of hockey is that there aren’t a lot of statistics. There are only a few concrete things that happen. A player plays his share of shifts which aggregate to a certain amount of time, takes his share of shots some of which score, and serves some penalties when he breaks the rules. When the game is over, the result is a win, a loss, or a tie. Anything else -- even the crediting of assists -- has a bit of a contrived quality to it. Same with the plus/minus rating.
Usually, a high plus/minus rating is touted as the mark of a good defensive player. Players who vie for the Selke Trophy, awarded to the league’s best defensive forward, are usually near the top of the league in plus/minus, but the Selke winner has only been given to the league leader once, Ron Francis in 1995.
Brian Engblom, who led the NHL in plus/minus in 1980-81 and is now a correspondent for ESPN.com, was a solid but not remarkable player who played on some very good teams. He defines puck possession as the most significant factor is a high plus/minus rating, stating, “there is no better defense than having the puck.” A player on a good team will tend to have a higher rating than a similarly skilled player on a bad team. Engblom also mentions that trends in a player’s plus/minus from game to game can be helpful to his team’s coaching staff.
What are its shortcomings?
The major fault of the plus/minus is that players on good teams have higher results than similarly-skilled players on bad teams. Reggie Leach is a Hall of Famer for his contribution to the Philadelphia Flyers’ Stanley Cup winning teams. He also won the Conn Smythe Trophy one year when the Flyers didn’t win the Cup. Yet he also recorded the fifth worst plus/minus rating of -61 playing for the unremarkable California Golden Seals in 1973-74. Breaking even on a bad team might be a major accomplishment, while breaking even on a good team might mean undisciplined play.
Another problem is that the plus/minus has no way to take into account what players’ roles might be, or how coaches try to match lines. One of the benefits for the home team during a hockey game is that the coach gets to make his line change after the visiting team makes theirs before faceoffs. This way, a coach can pit his most defensively sound line against the opponent’s most dangerous offensive line. If the home coach sees that visiting team has iced a less dangerous line, he can put out a defensively liable but hopefully offensively skilled line. The better defensive players -- the ones who are expected to have better plus/minus ratings -- have to do so with the assignment of facing better offensive players.
In any case, any attempt to make the plus/minus more meaningful would severely complicate its calculation.
NHL Plus/Minus Leaders
1968 - Dallas Smith, Boston Bruins; +33
1969 - Bobby Orr, Boston Bruins; +65
1970 - Bobby Orr, Boston Bruins; +54
1971 - Bobby Orr, Boston Bruins; +124
1972 - Bobby Orr, Boston Bruins; +86
1973 - Jacques Laperriere, Montreal Canadiens; +78
1974 - Bobby Orr, Boston Bruins; +84
1975 - Bobby Orr, Boston Bruins; +80
1976 - Bobby Clarke, Philadelphia Flyers; +83
1977 - Larry Robinson, Montreal Canadiens; +120
1978 - Guy Lafleur, Montreal Canadiens; +73
1979 - Bryan Trottier, New York Islanders; +76
1980 - Jim Schoenfeld, Buffalo Sabres; +60 (for some reason Jim Watson of the Flyers is often listed as leading with +53)
1981 - Brian Engblom, Montreal Canadiens; +63
1982 - Wayne Gretzky, Edmonton Oilers; +81
Emery Edge Trophy, sponsored by Emery Worldwide
1983 - Charlie Huddy, Edmonton Oilers; +62
1984 - Wayne Gretzky, Edmonton Oilers; +76
1985 - Wayne Gretzky, Edmonton Oilers; +98
1986 - Mark Howe, Philadelphia Flyers; +85
1987 - Wayne Gretzky, Edmonton Oilers; +70
1988 - Brad McCrimmon, Calgary Flames; +48
The NHL Plus/Minus Award (no sponsorship)
1989 - Joe Mullen, Calgary Flames; +51
1990 - Paul Cavallini, St. Louis Blues; +38
1991 - Theoren Fleury, Calgary Flames; and Marty McSorley, Los Angeles Kings; +48
1992 - Paul Ysabaert, Detroit Red Wings; +44
1993 - Mario Lemieux, Pittsburgh Penguins; +55
Alka-Seltzer Plus Award, sponsored by Alka-Seltzer
1994 - Scott Stevens, New Jersey Devils; +53
1995 - Ron Francis, Pittsburgh Penguins; +30
1996 - Vladimir Konstantinov, Detroit Red Wings; +60
Bud Ice Plus-Minus Award, sponsored by Anheuser-Busch
1997 - John LeClair, Philadelphia Flyers; +44
1998 - Chris Pronger, St. Louis Blues; +46
Bud Light Plus-Minus Award, sponsored by Anheuser-Busch
1999 - John LeClair, Philadelphia Flyers; +36
2000 - Chris Pronger, St. Louis Blues; +52
2001 - Joe Sakic, Colorado Avalanche; and Patrick Elias, New Jersey Devils; +45
2002 - Chris Chelios, Detroit Red Wings; +40
2003 - Peter Forsberg, Colorado Avalanche; and Milan Hejduk, Colorado Avalanche also; +52
2004 - Martin St. Louis, Tampa Bay Lightning; and Marek Malik, Vancouver Canucks; +35
Brian Engblom. “Sometimes, Plus/minus Equals Confusion.” ESPN.com. http://espn.go.com/nhl/columns/engblom_brian/1284866.html. November 7, 2002.
Arthur Etchells. “Research: Adjusted +/-, Factoring Out the Team.” BetterStatistics.com. http://www.betterstatistics.com/research_adjplusminus.aspx. November 7, 2002.
Phil Stamp, ed. The A to Z Encyclopaedia of Ice Hockey. http://www.azhockey.com/Nh.htm. November 7, 2002.
Budd Bailey. “Worst All-time Plus-minus Rating.” The Hockey Abstract. http://hockeyabstract.homestead.com/41902.html. November 14, 2002.
Stats gleaned from www.hockeysandwich.com, www.phillyflyers.com, www.faceoff.com, among others.