The Uncovered Truth About PDO and SH%

[Bedards Dad]

The issue with PDO for me is that it is connect, but its proponents, as a predictor of luck. Luck is not, imo, predictable.
IMO statistics are supposed to be about facts, and not associated with luck.

I don't believe it's about luck, it's about sustainability. Being far too high or far too low is very likely unsustainable over a long period of time. That's not to say there aren't outliers, but they are exactly that, an outlier and shouldn't be expected.

 

[Grulemieux]

Why the hell does this rule even exist?

 

[Ezekial]

You should do stand up

 

[TheDawnOfANewTage]

It seems as though NHL fans oft forget the somewhat obscure rule disqualifying teams from winning the Stanley Cup if they have a PDO that is too high. Similarly, and perhaps more obscure, is the rule stating that if a player on a team has too high of a shooting percentage, that also disqualifies the them.


Cited here:

46.15 Excessive PDO – Should a team's regular season PDO exceed 1050, that team will be ineligible to win the Stanley Cup, regardless of the outcome of the games in which they participate.

and

50.12 Unsustainable Shooting Percentage - When any individual player on a team has a regular season shooting percentage higher than 33%, that team will be disqualified and hence ineligible from winning the Stanley Cup


The infamous case of these rules actually being enforced was in 1928 when the Montreal Maroons advanced to the Stanley Cup Final against the New York Rangers. The Maroons went on to win that series, based on actual on-ice results, and capture the Stanley Cup with Babe Siebert scoring a series-clinching goal late in game 5 (the Final was a best-of-3 back then). Unfortunately for them and their fans, these rules, which had been buried in the rulebook, were brought to light. It turns out that Siebert's teammate Hooley Smith had a shooting percentage of 33.4%. Even more egregious, the team collectively had a regular season shooting percentage of 18.6%. Most appalling, and what ultimately ended up costing the Maroons the Stanley Cup, was their team regular season PDO of 1051.

This entire ordeal likely couldn't happen today with the speed of information transfer we now have, but one can see how in 1928 the coaches and players perhaps were not even aware of these rules - and how the Maroons were allowed to play all the way to the Stanley Cup Final before NHL President Frank Calder had to rightfully rip the Cup out of the hands of Maroons captain Dunc Munro.

Wait- what? Can’t tell if real or satire.

 

[wintersej]

The issue with PDO for me is that it is connect, but its proponents, as a predictor of luck. Luck is not, imo, predictable.
IMO statistics are supposed to be about facts, and not associated with luck.

But like the whole field of statistics is about probability and variance. That’s oversimplified here to mean “luck” but luck is only part of it. Obviously, if your team has Hasek, you are going to have a high save percentage and that is going to drive PDO. That ain’t luck. But having almost everyone is your top 9 shooting 15-20% without history showing that is normal for them? There is probably some luck in there. Maybe some system stuff, too. Maybe they all just got better at the same time. But, there is a high degree of probability there is some luck at play. You flip a coin 10 times, you might get heads 7 times. That doesn’t mean that forever you will always get heads 70% of the time.

 

[Ted Hoffman]

Is anyone else sick of advanced stats? I'm so over it.

I'm not sick of advanced stats. I'm sick of the continuing misunderstanding - not by casual fans, by people who do teh analtyics and created advanced stats - of what some stat really means or how to practically apply it, because they should all know better. Way too many people - and especially teh analytics people - and way too many takes still see correlation and thinks aha, there's the explanation! and run off accordingly.

PDO and winning percentage are highly correlated. PDO is nothing more than an aggregate of all team and individual performance, for offense and defense, split into two numbers that are added together. Are both of those two numbers that get added together highly correlated with winning percentage? No. Or, not nearly as much as PDO. [Which, this should already be raising questions, but it doesn't - so, we move on.] So all I have to do is increase "the sum of my goalie saving more shots" and "the sum of my skaters to score on more shots" and we're more likely to win more games, right? OK. How do I use PDO to adjust the roster, adjust the offensive and defensive schemes to improve my chances of winning? Playoff series are short, there's a hell of a lot more variability in results in 4-7 games vs. 82 games, how do I use PDO from the regular season to predict what's going to happen in the playoffs? Is there any practical application of PDO that I can reliably use for decision-making for say organizational planning, sports betting, or anything? But goddamnit, PDO is highly predictive! It's highly predictive, Bob!

Some like has CF% above X, and the xGF/xGA is above some ratio? Oh, look, they're doing really good? OK, why? Does that line have special synergy? Is someone carrying the others? Is it favorable line matchups? Have they just been on a heater and they're going to calm down? How do I apply this for other guys on the roster? Can I take this and build a roster where everyone in other places has "above average" stats and now on the same roster, they're still going to have "above average" stats or maybe be even better? And this goes to all kinds of advanced stats getting cranked out: lots of ooh, aah, completely lacking in context or explanation.

Which brings me to one of my all-time hates: if a stat is higher/lower than expected, it's explained away with "well, there's going to be regression to the mean" as if they or anyone else knows what the mean is. You don't know. I mean, I'm sure you think you do, you claim you do because of long-term averages and blah blah blah, but at the micro-level, at the player level, you have no clue what any player's "mean" is at any given point in their career until you have enough data to get a reliable sense of what they've done, by which time other things have changed and the observed historical mean may not be the expected mean going forward. Quit pretending you have any clue what "mean" is for something.

I've said it a number of times, I'll say it again: whoever figures out how to take all these stats and apply them in such a way that they produce reliable results going forward is going to make an absolute f***ing shitload of money, because that's going to be applicable to a huge swath of business applications. [Spoiler: it starts with understanding why some stat looks like it does.] Until then, everyone is figuratively pissing in the kiddie pool thinking they're making great art.

 

[Mattilaus]

I don't get why the point is deliberately misconstrued by the people who dislike stats or PDO. Nobody is saying a team with a high PDO can't win or won't win in the future, or that it will completely regress back to 100. They simply say that there is like to be some regression when it comes to sv% and shooting %. Can a team have a higher than average shooting % and sv%? Of course they can, but the further you go above average, the less likely it is to be sustainable. McDavid scores 150 points a season, that is WAY above average but is sustainable for him. If he had a stretch where he is on pace for 300 would we say that is sustainable? Of course not, and saying he will likely regress doesn't mean he is a bad player or that he won't still settle in at still above average production.

 

[KeithIsActuallyBad]

Canucks fans should remember well the 2015 series against the Flames, the PDO darlings. Despite the Canucks being the better team, the Flames got goals seemingly at will not to mention timely saves and a few comeback wins (including the decisive game 6)

...Then the Flames went to face a real team in Anaheim who promptly brushed them aside.

 

[Djp]

But like the whole field of statistics is about probability and variance. That’s oversimplified here to mean “luck” but luck is only part of it. Obviously, if your team has Hasek, you are going to have a high save percentage and that is going to drive PDO. That ain’t luck. But having almost everyone is your top 9 shooting 15-20% without history showing that is normal for them? There is probably some luck in there. Maybe some system stuff, too. Maybe they all just got better at the same time. But, there is a high degree of probability there is some luck at play. You flip a coin 10 times, you might get heads 7 times. That doesn’t mean that forever you will always get heads 70% of the time.

I agree. Probability can vary. some players can improve over time but prior stats can’t predict that If changes occurred.



if your top 6 scoring players have an increased shooting % might be attributed to system change.

 

[andora]

They’re not disqualified from winning the cup, teams that rely on PDO are simply rarely good enough to actually win the cup, and they get exposed in the playoffs by teams that rely less on luck.

The issue with PDO is it’s not controllable, sustainable or predictive. So a team racking up wins on the basis of PDO is s ticking time bomb, and their success isnt predictive in a way that you could reasonably say ‘this team has won a lot of games, therefore it is likely they will continue to win games’.

Could the heater last all the way to cup? Sure. Can you count on it? No. And without the heater, PDO-reliant teams fall fast.

How do you rely on a strong goalie save percentage and lower than average shots vs havimg a good goalie and not wasting low % shots

And if it is uncontrollable can it be unsustainable? Or for that matter be the basis of wins?

 

[Voight]

Is anyone else sick of advanced stats? I'm so over it.

I'm sick of hearing about them when there's little to no use for them

 

[ryan callahan]

I think people underestimate how much Elias Pettersson makes players around him better. Extremely selfless player. Builds trust in the locker room and other players are likely to follow suit. Defense, skating, shooting and unreal hockey IQ and passing. Built like a popsicle stick but will play physical if the game gets gritty.

 

[The Gr8 Dane]

PDO is dumb ask canucks fans how they feel about it , I'm sure they we're crying during the first half of the season having WON all those games fair and square and BANKING all those useless points in the regular season.

 

[Three On Zero]

Is anyone else sick of advanced stats? I'm so over it.

They are fine but people rely too heavily on them thinking they actually prove something. Advanced stats in the current form prove nothing and are highly subjective due to the nature of the sport. You can refute almost all of them

 

[Golden_Jet]

It seems as though NHL fans oft forget the somewhat obscure rule disqualifying teams from winning the Stanley Cup if they have a PDO that is too high. Similarly, and perhaps more obscure, is the rule stating that if a player on a team has too high of a shooting percentage, that also disqualifies the them.


Cited here:

46.15 Excessive PDO – Should a team's regular season PDO exceed 1050, that team will be ineligible to win the Stanley Cup, regardless of the outcome of the games in which they participate.

and

50.12 Unsustainable Shooting Percentage - When any individual player on a team has a regular season shooting percentage higher than 33%, that team will be disqualified and hence ineligible from winning the Stanley Cup


The infamous case of these rules actually being enforced was in 1928 when the Montreal Maroons advanced to the Stanley Cup Final against the New York Rangers. The Maroons went on to win that series, based on actual on-ice results, and capture the Stanley Cup with Babe Siebert scoring a series-clinching goal late in game 5 (the Final was a best-of-3 back then). Unfortunately for them and their fans, these rules, which had been buried in the rulebook, were brought to light. It turns out that Siebert's teammate Hooley Smith had a shooting percentage of 33.4%. Even more egregious, the team collectively had a regular season shooting percentage of 18.6%. Most appalling, and what ultimately ended up costing the Maroons the Stanley Cup, was their team regular season PDO of 1051.

This entire ordeal likely couldn't happen today with the speed of information transfer we now have, but one can see how in 1928 the coaches and players perhaps were not even aware of these rules - and how the Maroons were allowed to play all the way to the Stanley Cup Final before NHL President Frank Calder had to rightfully rip the Cup out of the hands of Maroons captain Dunc Munro.

Which rulebook, here is 23/24, not in there.

https://media.nhl.com/site/asset/public/ext/2023-24/2023-24Rulebook.pdf

Another parody thread.

 

[GOilers88]

I'm not sick of advanced stats. I'm sick of the continuing misunderstanding - not by casual fans, by people who do teh analtyics and created advanced stats - of what some stat really means or how to practically apply it, because they should all know better. Way too many people - and especially teh analytics people - and way too many takes still see correlation and thinks aha, there's the explanation! and run off accordingly.

PDO and winning percentage are highly correlated. PDO is nothing more than an aggregate of all team and individual performance, for offense and defense, split into two numbers that are added together. Are both of those two numbers that get added together highly correlated with winning percentage? No. Or, not nearly as much as PDO. [Which, this should already be raising questions, but it doesn't - so, we move on.] So all I have to do is increase "the sum of my goalie saving more shots" and "the sum of my skaters to score on more shots" and we're more likely to win more games, right? OK. How do I use PDO to adjust the roster, adjust the offensive and defensive schemes to improve my chances of winning? Playoff series are short, there's a hell of a lot more variability in results in 4-7 games vs. 82 games, how do I use PDO from the regular season to predict what's going to happen in the playoffs? Is there any practical application of PDO that I can reliably use for decision-making for say organizational planning, sports betting, or anything? But goddamnit, PDO is highly predictive! It's highly predictive, Bob!

Some like has CF% above X, and the xGF/xGA is above some ratio? Oh, look, they're doing really good? OK, why? Does that line have special synergy? Is someone carrying the others? Is it favorable line matchups? Have they just been on a heater and they're going to calm down? How do I apply this for other guys on the roster? Can I take this and build a roster where everyone in other places has "above average" stats and now on the same roster, they're still going to have "above average" stats or maybe be even better? And this goes to all kinds of advanced stats getting cranked out: lots of ooh, aah, completely lacking in context or explanation.

Which brings me to one of my all-time hates: if a stat is higher/lower than expected, it's explained away with "well, there's going to be regression to the mean" as if they or anyone else knows what the mean is. You don't know. I mean, I'm sure you think you do, you claim you do because of long-term averages and blah blah blah, but at the micro-level, at the player level, you have no clue what any player's "mean" is at any given point in their career until you have enough data to get a reliable sense of what they've done, by which time other things have changed and the observed historical mean may not be the expected mean going forward. Quit pretending you have any clue what "mean" is for something.

I've said it a number of times, I'll say it again: whoever figures out how to take all these stats and apply them in such a way that they produce reliable results going forward is going to make an absolute f***ing shitload of money, because that's going to be applicable to a huge swath of business applications. [Spoiler: it starts with understanding why some stat looks like it does.] Until then, everyone is figuratively pissing in the kiddie pool thinking they're making great art.

The whole PDO thing makes me think of the old, "Gotta be good to be lucky, and lucky to be good."

Also, good post.

 

[Clamshells]

Which rulebook, here is 23/24, not in there.

https://media.nhl.com/site/asset/public/ext/2023-24/2023-24Rulebook.pdf

Or is this a parody?

Its real, its in the other rulebook that isn't publically available. The same one that says the refs have to make bad calls against your team.

 

[Ted Hoffman]

I don't get why the point is deliberately misconstrued by the people who dislike stats or PDO. Nobody is saying a team with a high PDO can't win or won't win in the future, or that it will completely regress back to 100. They simply say that there is like to be some regression when it comes to sv% and shooting %.

Let's just stop there.

Is there really "like [sp] to be some regression?" Maybe. Maybe not. I don't know. Do you know? Does anyone know? No, no one does. All we know is there's an expectation of what "the mean" is [which again, is probably unknowable in the context to which the regression comment is lobbed] and an implied belief that obviously, a stat has to tend toward that value over the long-term which can not happen for all kinds of reasons.

When might this regression occur? Tonight? Tomorrow night? 3 weeks from now? Right before the playoffs start? 2 years from now? No one knows. Well, eventually it will. OK, thanks Baba Vanga, that's really helpful for me trying to analyze what's going on with a team and understand what to expect. Going to be great when I go into a team's front office and things are going great and someone offers up hey I know you're all in a great mood, the team is doing fantastic in the standings, but this stat says it's unsustainable, you guys are going to regress to the mean. No, I have no idea what the means. No, I have no clue when that's going to happen. No, I have no clue what you can do to prevent it. What do you mean you're calling security? Look, I'm trying to help you folks out!

While the past is obviously not a perfect predictor of the future, it is a predictor and we're arguing over how much weight to put on it. Or, in my world, how much credibility to assign to it. When a stat outperforms expectations [either positively or negatively], you have to ask is this real, or is this a fluke? And the longer it outperforms, the more you have to ask that question - and simply being lazy and saying ah, well, it's going to regress to the mean is a worthless comment because it lacks both context and knowledge.

 

[ThatGuy22]

The issue with PDO for me is that it is connect, but its proponents, as a predictor of luck. Luck is not, imo, predictable.
IMO statistics are supposed to be about facts, and not associated with luck.

PDO is a set of a facts, that indicate when a team/player may be getting lucky or unlucky based on historical data.

It's all fact based. We know what these individual players have done in the past. We know based on 100s of seasons by individual teams what tends to happen.

It's entirely fact based

 

[kingsholygrail]

It seems as though NHL fans oft forget the somewhat obscure rule disqualifying teams from winning the Stanley Cup if they have a PDO that is too high. Similarly, and perhaps more obscure, is the rule stating that if a player on a team has too high of a shooting percentage, that also disqualifies the them.


Cited here:

46.15 Excessive PDO – Should a team's regular season PDO exceed 1050, that team will be ineligible to win the Stanley Cup, regardless of the outcome of the games in which they participate.

and

50.12 Unsustainable Shooting Percentage - When any individual player on a team has a regular season shooting percentage higher than 33%, that team will be disqualified and hence ineligible from winning the Stanley Cup


The infamous case of these rules actually being enforced was in 1928 when the Montreal Maroons advanced to the Stanley Cup Final against the New York Rangers. The Maroons went on to win that series, based on actual on-ice results, and capture the Stanley Cup with Babe Siebert scoring a series-clinching goal late in game 5 (the Final was a best-of-3 back then). Unfortunately for them and their fans, these rules, which had been buried in the rulebook, were brought to light. It turns out that Siebert's teammate Hooley Smith had a shooting percentage of 33.4%. Even more egregious, the team collectively had a regular season shooting percentage of 18.6%. Most appalling, and what ultimately ended up costing the Maroons the Stanley Cup, was their team regular season PDO of 1051.

This entire ordeal likely couldn't happen today with the speed of information transfer we now have, but one can see how in 1928 the coaches and players perhaps were not even aware of these rules - and how the Maroons were allowed to play all the way to the Stanley Cup Final before NHL President Frank Calder had to rightfully rip the Cup out of the hands of Maroons captain Dunc Munro.

 

[Bank Shot]

It's more sustainable long term to be the team dominating in terms of creating and limiting scoring chances than the team dominating through their shooting/save percentages. It's really that simple. The latter is going to be subject to more variance.

Its crazy that there is even a debate around this.

 

[andora]

PDO is a set of a facts, that indicate when a team/player may be getting lucky or unlucky based on historical data.

It's all fact based. We know what these individual players have done in the past. We know based on 100s of seasons by individual teams what tends to happen.

It's entirely fact based

Can luck be a fact?

 

[Breakers]

Another thread on PDO

LOL

 

[andora]

Another thread on PDO

LOL

Performance Discrediting Optics

 

[Steddy33]

Wait- what? Can’t tell if real or satire.

Explains a lot.