Team +/- is the best indicator of making the playoffs

 

The object of hockey is simple. Score more goals than the opponent. But the current NHL point scoring system for team wins/ties can hide extra information. Here are two scenarios:

1. Toronto Maple Leafs beat Tampa 10-0
   
2. Toronto Maple Leafs beat Tampa 1-0
   

In both of those scenarios, Toronto gets 2 points and Tampa gets 0. But it's the scoreboard that clearly shows the difference in performance for both teams. In Scenario A, Toronto shows how strong they are while Tampa shows how weak they are.

Points don't do a great job in explaining to what degree a team wins and loses. It's too bad because all sorts of interesting things start to happen when we get down to a team's overall +/- (that's goals for minus goals against). A team's +/- is a great predictor for playoff appearances.

From the 2005-2008 Seasons:

• 91% of teams that made the playoffs had a positive +/-. Only four times did a team make the playoffs over the last three seasons that had with a negative +/-. Boston 2007-08 being the worst at -10.
  
• Those teams with a negative +/- miss the playoffs 83% of the time. Only seven times did a team with a positive +/- miss the playoffs. The Colorado Avalanche of 2006-07 and Buffalo Sabres of 2007-08 are some of the notable exceptions.
  
• The coefficient correlation between a teams +/- and winning % is +0.92. That means that it is a virtual lock. Teams with a good +/- have a good winning percentage and vis. versa.
  

So what does this mean? Well it becomes easier to pin-down the reasons for why a team made the playoffs or why it didn't. The NHL opens itself up to this kind of evaluation because they keep track of individual player's time on the ice and their individual +/-. The NHL.com might be the best site out of all the major leagues for rich statistics. Future posts will look at different ways to evaluate players and their impact on helping/hurting their teams runs to the playoffs based on +/- and save % and other gold nuggets waiting to be mined at the NHL.com.

 

Caveats:
The strength/weakness of a teams schedule is not included here. Ideally, it would be. Beating the 2008-09 Boston Bruins by 3 goals is more impressive than beating the NY Islanders by four.