Only four games into the season, we’re already asking ourselves whether the current Oilers team is better than the trainwreck that preceded it in 2012-13. The 2013-14 Oilers have a per-game Corsi% average of 49.2%. At the same point last year, the Oilers were a 47.2% Corsi team. There doesn’t seem like a whole lot to go on here, but in this article I’ll try to explore whether we can make any conclusions yet.
For the purposes of this piece, I’ll purely be examining shot differential, or Corsi, which is an important part of team strength.
Though we’re only 4 games into this season, the 2012-13 Oilers have already played an entire (albeit truncated) season of 48 games. From that sample, we observe a mean game Corsi percentage of 44.4%, meaning that on average, that team obtained 44.4% of shot attempts at even strength in a game. The standard deviation around this mean was about 6%. In the piece I did earlier about player Corsi, it was observed that the standard deviation of players is around 12%, meaning that teams have a much tighter distribution around their means in terms of game performance and less extremes. Even considering how bad that Oilers team was last year, they only had one game below 30% Corsi percentage. In just last night’s game vs the Habs, there were 4 Oilers who were below 30% Corsi%.
Here’s a histogram that shows how the 2012-13 Oilers did in per-game Corsi% over their 48 games:
We see that they had 9 games between 44% and 46% Corsi percentage, 7 games between 48% and 50% Corsi percentage, etc. The label to the far left should really say <32%, as that data point was actually 26.6%.
To try to visualize this problem, I’ll again use Monte Carlo simulation, in this case to simulate what 10,000 seasons played by the 2012-13 Oilers might have looked like based on their observed mean and standard deviation last year. Then, we’ll plot 95% confidence interval lines, to show the 2 points in each game of the season where 95% of observations would fall between in terms of our 10,000 simulated seasons’ accumulated average Corsi%. Finally, we’ll plot this year’s season and compare against these lines.
After 4 games, we can see that the 2013-14 Oilers are at 49.2% accumulated average Corsi% (ending in the yellow star). Comparing that performance vs the 95% confidence interval, we can see that it is just inside the upper 95% boundary, meaning we cannot yet conclude whether the 2012-13 Oilers would not have been capable of starting a season as well as the 2013-14 Oilers have. In the simulated data, 6.2% of our 10,000 seasons played by the 2012-13 squad had a 4-game accumulated Corsi percentage that matched or was higher than the 4 game start seen in the current season by the 2013-14 team.
It’s interesting to point out the actual 2012-13 data — that team started relatively high as well, before plummeting towards their eventual season average of about 44%. If the current squad can just maintain their 49.2% Corsi% until game 7, we’d be able to conclude that the 2012-13 squad would have been unlikely to have started a season the way the 2013-14 squad has. Also, we’d be able to make a similar claim after their next game (the 5th, versus the Leafs on Saturday) if their accumulated Corsi% is 49.7% or higher — this would require them to post a 51.8% Corsi percentage against the Leafs or higher.