The Fleury Numbers
I always preface these articles the same way.
Statistics are a passion of mine, I am a numbers nerd at heart. But that doesn’t mean they are the be-all, end-all of hockey analysis.
That being said, statistics provide us with a great insight into what the on-ice eye test says about certain players.
Today, I wanted to dissect a few advanced numbers on Marc-Andre Fleury.
With the news about Tomas Vokoun’s blood clot issue on everyone’s minds, the Pittsburgh hockey world has a nervous anticipation about it in regards to the Penguins goaltending situation.
The website Hockey Goalies carries a lot of awesome advanced statistics about goaltenders. Let’s dive in and take a look at Marc-Andre Fleury’s 2012-13 season.
Goals Above Replacement
GAR, for short, is a great statistic that tells us how many goals a goaltender saved above a league average goaltender.
For HockeyGoalies.org – replacement is 1.5% below league average. So, essentially, this statistic takes Marc-Andre Fleury’s numbers and breaks them down against 1.5% below the league average, the standard deviation for a “replacement” goaltender.
For you math people, here is the formula to find this number:
GAR = ((1 – (League Average SV% – 0.015)) * (Shots Faced)) – (Goals Against)
Fleury GAR 2013/13 Regular Season: 16.9
GAR 2012/13 Post-season: -3.8
For comparison, Tomas Vokoun had a regular season GAR 11.9, so Fleury excelled there, which we all saw throughout the year.
The issue is the post-season. The bottom fell out and Fleury actually allowed 3.8 more goals against what a league replacement would. For a comparison, the GAR for Vokoun’s post-season play was 9.1, a career high for him.
This discrepancy is alarming at best.
Below Average Performances
I’ll let HockeyGoalies.org explain this one:
For each opponent in the league, a “benchmark save percentage” is developed, based upon their non-empty net shooting percentage. If we make the (admittedly simplifying) assumption that shots faced in a single game represent a binomial distribution, then we can estimate (for each game) how many standard deviations above (or below) average a goaltender’s actual game performance represented.
Performances within 0.5 standard deviations of average are grouped as “average”, with performances below that (and above that) grouped as “below average” (and “above average”). Season totals are weighted by shots faced in each game.
So, in layman’s terms, we’re looking at what percentage of the time Marc-Andre Fleury performed below the league average for a goaltender.
The next two numbers from the last two playoff runs might shock you.
Fleury BAVG 2011-12 Post-season: 68%
Fleury BAVG 2012-13 Post-season: 57%
In fact, in the 2011-12 season, Fleury performed above average in 0% of his performances. To boot, the year the Penguins won the Stanley Cup, Fleury only performed above average 21% of his performances.
In comparison to the last three regular seasons, where Marc-Andre Fleury’s below average percentage never exceeded 27%, these numbers are a bit shocking.
For comparison again, Tomas Vokoun performed below average in only 10% of his post-season appearances. Or, essentially, two games.
This one is a little complicated.
Let’s say for example, the average goaltender in the NHL has a save percentage of 90% and faces 100 shots on goal. We then know that an average goaltender allows 10 goals on 100 shots.
But suppose our specific goaltender allows only 8 goals on those 100 shots? How do we know how far above-average he was?
ZSCORE = (92 – 90) / SQRT (100 * 0.9 * 0.1) = 0.67, indicating that the goaltender was above average but not in a statistically significant fashion.
Truly remarkable performances (good and bad) start at about 2 standard deviations away from average, and the larger the number, the more significant.
Fleury Z-Score 2011-12 Regular Season: 0.0
Fleury Z-Score 2012-13 Regular Season: +.04
Now, take a look at these differences.
Fleury Z-Score 2011-12 Post-Season: -4.2
Fleury Z-Score 2012-13 Post-Season: -1.9
These numbers are a backup to the meltdown’s we see in the playoffs for Marc-Andre Fleury. We can now gauge how truly off the mark he’s been.
It’s no secret that the Penguins success, now and in the post-season, is going to ride on Fleury. These numbers simply cannot replicate themselves if the Penguins are to be successful.