Sunday, July 21, 2013

Why the NHL's new conference alignment is unfair for Eastern teams

Check out this post on the new version of Rink Stats.
On Friday the NHL released the 2013-2014 regular season schedule. This season will be the first played under the new conference and division alignment which sent Winnipeg west and Columbus and Detroit east. A key aspect of the new alignment is that there is an imbalance in the number of teams in the East (16) and in the West (14). In this post I'll discuss a paper I wrote a couple months back (How the West will be Won: Using Monte Carlo Simulations to Estimate the Effects of NHL Realignment). In the paper, I show that because 8 teams make the playoffs from each conference, the new alignment and playoff qualification rules unfairly disadvantage Eastern Conference teams.

Specifically, I'll show that the 8th seed in the East will (on average) be 2 or 3 points better in the standings than the 8th seed in the West. And I'll show that about 40% of the time, the 9th seed in the East would have made the playoffs if they were in the West (compared to just 20% of the time when the inverse is true).

Monday, July 15, 2013

Should you shoot first or second in a shootout?

Check out this post on the new version of Rink Stats.
I've always been interested in the strategy that goes into shootouts in the NHL. Each coach must first choose three players to take the shootout attempts for their team, and then they have to decide the ordering of those players. In addition, the home team gets to decide whether to shoot first or second.

80% of the time, the home team chooses to shoot first in the shootout. In terms of strategy, this seems like the proper course of action. Somebody better versed in economic game theory could probably prove this better than me, but the basic intuition is based on the fact that the probability of scoring on any shootout shot is less than 50%. If the team that shoots first scores, then the other team's shooter probably feels more pressure to score. Likewise, if the first team fails to score, the odds are still in that team's favor that the shootout score will remain tied (since there's still less than 50% chance of the second team to score).

In this post, I want to see whether the team that shoots first actually wins more shootouts. By looking at the 900+ shootouts that have happened in the NHL since 2007-2008, I find that there appears to be some evidence that shooting first gives you a slightly better probability of winning. Somewhat surprisingly though, I also find that teams tend to do worse in shootouts at home than on the road.

Monday, July 8, 2013

Are shorthanded goals momentum killers?

Check out this post on the new version of Rink Stats.
Shorthanded goals are powerplay killers. You hear this all the time when you watch hockey games. But how true is this conventional wisdom? It certainly doesn't seem very common for a team to concede a shorthanded goal and then quickly follow it with a powerplay goal of their own. But it's also true that a majority of powerplays don't result in a goal, regardless of whether a SHG was conceded or not.

The question of how much SHGs kill a team's momentum on the powerplay is one that I've always thought about. Below, I take a first crack at answering the question. I show that having a SHG scored against you lowers your probability of scoring a PPG by about 10 percentage points. And early shorthanded goals have a bigger effect on a team's powerplay momentum that late ones.