Does Hockey Math Work?

"Hockey is too complex for numbers to help understand, let alone predict..."


Does this sound familiar?  It should, it's one of the major arguments presented by those who do not appreciate the predictive value of math.  In May of 2010, I wrote an article about using some basic advanced stats to give Oilers' fans a general idea of what they should expect from each 2009-2010 player for the 2010-2011 season.  I relied heavily on On Ice Sh % and On Ice Sv % (PDO), both of which can be found at www.behindthenet.ca, courtesy of the dashing Gabriel Desjardins as well as career shooting % vs. 09-10 shooting % to determine which players were likely to regress.

After the jump, we'll take a look at those predictions and how they panned out.

Expected counting numbers increase

Andrew Cogliano - his 09-10 shooting percentage was less than half of his previous career average.  Whether his previous career average was sustainable was the subject of fierce debate on a number of different sites, but he's definitely better than a 7.2% shooter.

Cogliano's shooting percentage rose slightly, from 7.9 to 8.5 percent.  Cogliano tallied one more goal (11).

Fernando Pisani - he might be on the downside of his career, but his 09-10 shooting percentage was only 7.4%, compared to his previous career average of 13.3%.  If he does leave Edmonton, he's leaving with his value lower than it's been since he left Providence.

Pisani left Edmonton, much to the dismay of our staff,  for the greener pastures of Chicago after not being offered a contract.  Pisani's shooting percentage rebounded to 9.7% from 7.4% and he scored 7 goals and collected 9 assists.  He totaled 16 points, more than the Oilers' entire fourth line combined.

Ryan Whitney - he scored a boatload of points after he was acquired in exchange for Lubomir Visnovsky, but on the season he was still below his career shooting percentage.

Whitney actually duplicated his 09-10 shooting percentage, scoring only two goals in 35 games.

Sheldon Souray - everything about his game seemed to suffer last season, and his shooting percentage of 3.5% was about half of his career rate of 6.6%.

Not available.  Souray was banished to the hinterlands by the management cabal at Rexall Place.

Taylor Chorney - he shot zero percent, so there's nowhere to go but up, right?

Incomplete.  Chorney scored on 1 of his 13 shots on goal before falling to injury.

 

Expected counting numbers decrease

Aaron Johnson scored four goals this year (a career high) on shooting percentage of 11.1%. Don't expect him to match that again.

Not available - Johnson spent the entire season in the AHL with the Milwaukee Admirals.

Dustin Penner scored 32 goals on 15.8% shooting, nearly 30% higher than his previous career average. He did, however, break 200 shots and if he can do that again, the Oilers should expect 25 goals out of Penner.

Penner kept his shooting percentage high for most of the year, as he shot 15.3% for the Oilers and was on pace for 27 goals before being traded. After the trade, he hit an unlucky streak and only shot 5.6% for the Kings, scoring just two goals. His season totals were 13.8% and 23 goals.

Gilbert Brule - I touched on Brule's performance in December and hoped that the Oilers wouldn't open the vault for Brule during his upcoming contract negotiations. Jonathan Willis did much the same thing recently and came to many of the same conclusions I did - Brule is worth a signing, but if they're going to have to spend big on him, they should look to trade him. Why? Well, for starters, Brule's shooting percentage is a red flag. He doubled his career shooting percentage to get his 17 goals.

Before the 2009-2010 season, Brule's career shooting percentage was 7.1%. His 2009-10 season raised it to 9.8%. In 2010-11, his shooting percentage fell from 14% to 9.7% and he scored just 7 goals in 41 games.

 

Underlying stats expected to improve

Fernando Pisani - Like his shooting percentage, his underlying numbers fell off sharply as well. He was -17 in 40 games. Even with an average PDO, Pisani would have been -7 in 40 games. He's clearly not the tough-minutes beast of burden that Craig MacTavish used to throw over the wall in all situations, but if he can stay healthy, he should be able to bounce back - way back - against second and third-level minutes.

Pisani's PDO rebounded to 1011 and his even strength goal differential was +1. That's a bounce.

Mike Comrie - Comrie's terrible PDO was sunk by the .891 save percentage and he was -9 at evens in only 43 games. Get him back to an average PDO and Comrie was even at evens.

Incomplete - Comrie played only 21 games before suffering a hip injury in Pittsburgh

Patrick O`Sullivan - goat #2 for the Oilers in 09-10, O'Sullivan suffered through a brutal year by nearly every traditional and advanced measure. He was -30 at even strength and didn't face the toughest comp, though he did for a portion of the year which was spent with Horcoff and the anchor of the S.S. Oilers, J.F. Jacques. his PDO was an abysmal 956 and yes, his 5.8% shooting percentage had an effect on that, but both are bound to improve next year. With a PDO of 1000, O'Sullivan would be -8 at even strength.

O'Sullivan appeared in only 31 games for Carolina and Minnesota, but his PDO did rebound to 1016 and he was only a -1 at even strength in those 31 games, a -3 pace compared to his -30 in Edmonton last year

Ryan Potulny - Potulny had a breakout season, scoring 15 goals and adding 17 assists. He was the only shooting threat the Oilers had other than Dustin Penner and found himself on the power play quite often. However, he was also -19 at even strength. Even though Potulny himself shot 9.9%, his team on ice shooting percentage was only 6.63% and he wasn't helped by the .891 save percentage behind him. That 959 PDO did his numbers no favors. Potulny won't get those power play minutes this coming season, so he'll be hard-pressed to duplicate his counting numbers, but with an average PDO last season, he would have been -3, rather than -19.

Incomplete. Potulny appeared in only 10 games for the Blackhawks and Senators.

Shawn Horcoff - goat #1 for the Oilers in 09-10 and to a vociferous portion of the fan base every year since the Stanley Cup Finals run. Horcoff played with a bum shoulder for a large portion of the year and it showed. He was -28 at even strength this season and a look at the underlying numbers shows why. His PDO was a brutal 960 on the back of his .891 save percentage. Crank his PDO back up to 1000 and he would have been -6 at evens last year. Considering the quality of competition that Horcoff faced and the linemates he was saddled with, -6 is a fantastic year.

Horcoff's PDO regressed from a 960 to 1008 and he went from -28 at even strength to -2.

Sheldon Souray - not only was his shooting percentage half of what it should have been, when he was healthy, his teammates weren't giving him much help. His even strength save percentage was a team low .881. Souray was -14 at evens, but with an average PDO, he would have been +2. Whoever ends up taking Souray off of Edmonton's hands has a chance of landing a steal, if he can only stay healthy...

Not available due to that whole hinterlands and cabal thing.

 

Underlying stats expected to decline

Ladislav Smid - Smid's PDO wasn't obscene at 1021, but his underlying numbers were built largely on the back of his partnership with Visnovsky playing against third minutes. He was +5 at even strength, but with an average PDO, he would have been -3. If the Oilers can continue to protect Smid and get him a partner that can pass, Smid might not crash back to earth. Throw him out against second minutes with a similarly-skilled defenseman and look out below.

Smid's PDO regressed from 1021 to 985 and he went from +5 at even strength to -5 at even strength. The silver lining was his stable Corsi, despite losing Lubomir Visnovsky as his regular partner.

Zack Stortini - Bruce will argue this point, but Stortini was +1 at evens with the highest even strength save percentage for any full-season Oiler at .937. His PDO of 1034 is primed for a fall, and given an average PDO, he would have been -6.

Stortini's PDO regressed from 1034 to 997 and Stortini went from +1 in 691 minutes to a -2 in 225 minutes.

 

Conclusions

I made 16 small predictions from the basic math.  Six of them were incomplete or not available.  Of the remaining 10, 8 of them were spot on and the 9th, Cogliano's shooting percentage and counting numbers, improved slightly.  The 10th, Whitney's shooting percentage, stagnated.  The predictions were 90% accurate which tells me that even the simplest of advanced stats have predictive value.

Math, it works.

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