Saturday, April 11, 2009

NHL Rules Can Give a Team a Good Reason to Score on Themselves

The NHL’s rules for breaking ties in the standings contain a major flaw that provides clear incentive for a team to put the puck into their own net late in a close game at the end of the season.

This didn’t happen this season, but consider the following scenario that demonstrates how possible it is:

First we need to change history just slightly, involving these 2 games:
Oct 10th: St Louis Blues 5, Nashville Predators 2 becomes Blues 3, Predators 2, in OT
Nov 22: St Louis Blues 2, Minnesota Wild 1 becomes Wild 2, Blues 1

That gives the Predators 1 additional point, and gives 2 of the Blues’ points in the standings to the Wild. That slightly tightens up an already close race for the eighth and final playoff spot in the Western conference. We can easily imagine things unfolding such that on Friday April 10th, the Blues could have been in 8th place, a point ahead of the Wild, and 2 points up on the Predators.

That night, Nashville was in Minnesota for their final game of the season (the Wild still had a game to play after that). Late in the 3rd period, Nashville leads 2-1. Coach Barry Trotz calls a time out with less than a minute left. The commentators are wondering why, since the extra break allows Minnesota’s top line to get a bit of extra rest as they pull their goalie for the extra attacker. After the time out, the faceoff is in the Nashville end. The Predators’ captain, Jason Arnott, wins the faceoff, and pulls the puck back towards his own goal. Goaltender Pekka Rinne steps aside, deliberately letting the puck go in the net. What the hell is going on?

Coach Trotz has figured out that in order to make the playoffs, the Predators must beat the Wild in overtime, not regulation time. The reasoning for this surprising conclusion follows.

A regulation win would tie the Predators with the Blues for the last playoff spot. The first tie-breaker is wins, and both teams have 40. The second tie-breaker is points earned in head-to-head games, and the Blues would win that tie-breaker, 8 points to 7 based on the results of games between them:

Oct 10th Nashville 4 @ St Louis 5 (OT)*
*this is a result we changed from the actual result
Nov 25th St Louis 1 @ Nashville 0 (OT)
Dec 8th Nashville 3 @ St Louis 6
Feb 12th St Louis 3 @ Nashville 4
Feb 19th St Louis 2 @ Nashville 1 (OT)
Feb 21st Nashville 2 @ St Louis 0

Total points of 12 possible:
Nashville: 7 points
St Louis: 8 points

So a 2-way tie between the Blues and Predators would result in the Blues advancing to
the playoffs. But if that April 10th game goes to overtime before the Predators win, the
Wild pick up a point, and now it’s a 3-way tie for 8th place. The NHL rules (from say:

If two or more clubs are tied in points during the regular season, the standing of the
clubs is determined in the following order:
  1. The fewer number of games played (i.e., superior points percentage). {this is always equal at the end of the season}
  2. The greater number of games won.
  3. The greater number of points earned in games between the tied clubs. If two clubs are tied, and have not played an equal number of home games against each other, points earned in the first game played in the city that had the extra game shall not be included. If more than two clubs are tied, the higher percentage of available points earned in games among those clubs, and not including any "odd" games, shall be used to determine the standing.
  4. The greater differential between goals for and against for the entire regular season.

Here are the results of the other games among these 3 teams:

Dec 6th Minnesota 0 @ Nashville 1
Feb 6th Nashville 2 @ Minnesota 1
April 10th Nashville 3 @ Minnesota 2 (OT)

Total points of 4 possible
Nashville: 4 points
Minnesota: 1 point
(The February 6th result is ignored, as it is the “extra” home game for the Wild.)

Nov 22 St Louis 1 @ Minnesota 2*
*this is a result we changed from the actual result
Dec 3rd St Louis 0 @ Minnesota 4
Dec 20th Minnesota 2 @ St Louis 4
Mar 15th Minnesota 3 @ St Louis 5

Total points of 8 possible
St Louis: 4 points
Minnesota: 4 points

Here’s how the 3-way tie gets resolved (taking into account the 2 game results we had to
change from what actually happened to get this scenario to play out):

Nashville vs St Louis: 7 points out of a possible 12
Nashville vs Minnesota: 4 points out of a possible 4.
Total: 11 points out of a possible 16, for a winning percentage of .6875

St Louis vs Nashville: 8 points out of a possible 12
St Louis vs Minnesota: 4 points out of a possible 8
Total: 12 points out of a possible 20, for a winning percentage of .6000

Minnesota vs St Louis: 4 points out of a possible 8
Minnesota vs Nashville: 1 point out of a possible 4
Total: 5 points out of a possible 12, for a winning percentage of .4167

So the result in a 3-way tie is that Nashville emerges with the best winning percentage in evenly-balanced games among the 3 tied teams, and advances to the playoffs (assuming that both Minnesota and St Louis lose in regulation time in their final games of the season on April 12th). Nashville therefore has a clear incentive to tie the game and force overtime, in order to keep their playoff hopes alive.

We could propose a better method of breaking ties in the standings that might avoid this problem, but the real reason this flaw exists is that the NHL rules for allotting points in the standings do not make an NHL game a zero-sum game. That is, you can give your opponent a point in the standings by going to overtime, without necessarily giving anything up. The solution is simple: change the rules to give teams 3 points for a regulation win, 2 for an overtime/shootout win, 1 for an overtime/shootout loss, and 0 for a regulation loss. Now any point earned by your opponent is a point your team did not get, and there can be no incentive to give points away. To preserve the integrity of the game, the NHL should make this rule change for the 2009/2010 season.

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