QUANTITY vs QUALITY
there’s little evidence that teams or players can get consistently outshot while still getting better chances.
over the long term, we can largely ignore shot quality — not because it doesn’t exist, but because it tends to even out over time.
The pursuit of shot quality will inevitably lead to shot quantity.
Bottom line: shot distance/location/quality is just a tiny sliver of shooting percentage (both for and against.) When you factor in the 33% regression to the mean we see in odd and even samples, shot quality accounts for just under 10% of team shooting percentage.
GOALS = SHOTS X SH%
Goals = Shots x Shooting Percentage
one can trade ‘shots’ for ‘shooting percentage’.
It is much easier to increase shots on goal than it is to increase shooting percentage.
it turns out that the quality of shots is a very poor predictor of shooting percentage. And this means that shooting percentage is largely about offensive skills.
OUTSHOOTING IS BETTER THAN SHOOTING FOR PERCENTAGES
In the long run, teams that outshoot generally have a better chance to achieve success. Over the course of a single season, however, it can be the team that rides a hot streak in terms of percentages that ends up on top of the standings
If a team is returning most of its key players and has the same coach or a similar coaching philosophy there is good reason to expect a similar SF/SA in 2009-10.
As long as the Red Wings and Sharks continue to pepper opposing goalies with shots they will win games even with mediocre percentages.
Teams that are relying on percentages rather than outshooting for their success are more likely to be susceptible to large swings in the standings depending on the luck of their shooters/goaltenders.
SHOTS ON GOAL AND STANDINGS POINTS
(Nov 2009)
The findings establish that there is a 0.48 correlation between shots on goal and accumulating points in the standings
a higher number of shots on goal will generally lead to a higher ranking in the standings
Talent, however, will dictate just how far out of the basement those teams rise.
OUTSHOOTING LEADS TO WINNING
From this it follows that the team that habitually outshoots at even strength will usually outscore. And the team that outscores at even strength will win.
RELATIONSHIP BETWEEN OUTSHOOTING AND WINNING
While the relationship between outshooting and outscoring may not be apparent over brief periods, the teams that succeed at even strength over the long run are those that spend more time in the opposition's end than their own.
The overall message is the same: as the season moves forward, the relationship between outshooting and outscoring at EV grows stronger.
Shooting % has low predictive value; shot volume on the other hand….
SHOT GENERATION VS SHOT PERCENTAGE
(Nov 2010)
As you can see, shooting percentage (opportunity capitalization) has a much stronger relationship with scoring goals than getting shots (opportunity generation). What about the defensive end of the game?
Again, opposition capitalization rates are much more correlated with scoring goals than opportunity generation.
Controlling the play and generating shots does not mean you’ll score goals (just ask any Maple Leaf fan), having the talent to capitalize on those opportunities is what matters most.
SCORING CHANCES AND SHOT TOTALS
(June 26, 2012)
shot quality differences are negligible,
There is a strong correlation between shot differential and scoring chance differential, so the simple shot differential tells us most of what we need to know.
shot differential is very important and shot quality effects are minor.
Dividing a player’s scoring chance differential by his shot differential (SC% / Fenwick) gives us a metric assessing how much of a shot quality edge the team had with him on the ice that year.
Whatever tendency certain players might have for driving their team to get more scoring chances than a simple shot differential predicts is small and swamped by random noise. This suggests tracking scoring chances isn’t adding much information to the readily available shot differential numbers.
SHOOTING PERCENTAGE AND SHOT RATES
In any given season, a player's point scoring rate is much more heavily driven by the shooting percentages than the shot rates.
It turns out that shooting percentages aren't very repeatable. The variance in shooting percentage is a much bigger factor than either the shot rate or the talent component
However, shot rate remains both more repeatable and more predictive of future point scoring.
It is critical to bear in mind that a single year's shooting percentage data is almost entirely noise. When we set expectations for a player, we need to look at multiple years of shooting percentage data and remember that whatever happened last month or even last year is pretty close to meaningless.
SHOT DIFFERENTIAL AND SHOOTING PERCENTAGE
It is clear that teams give bigger rewards for a player helping his team to shoot for a high percentage than for helping his team get a lot of shots.
A strong shot differential is a much more repeatable talent than a strong on-ice shooting percentage
Most teams don’t give out contracts because of Corsi. But a team that does will get more wins out of their budget than a team that follows the conventional path and overvalues finishing talent.
IS QUALITY OVER QUANTITY EVEN POSSIBLE
(Oct 2013)
Quality over quantity, you might say.
It’s a theory that makes some sense. If the Leafs can dominate the shot quality category, then that would explain why they can be consistently outpossessed and outshot and still expect to win
There’s one problem: Advanced stats say that shot quality doesn’t exist. Or, more accurately, that it doesn’t exist as a repeatable phenomenon.
There’s no statistical evidence that certain teams (or systems, or coaches) can maintain a shot-quality advantage over the long term. If one team — let’s call it, say … the Toronto Maple Leafs — has a stretch when it’s better in this area than others, well, that’s just good luck showing up again.
FIREWAGON HOCKEY – DOES EVENT RATE MATTER
it seems appropriate to ask whether fast-paced, high-event teams are, in fact, unsound. How much does the pace of a team’s game matter?
A team that consistently plays games in which tons of pucks are being thrown at the net can be characterized as a firewagon squad, while a low rate of attempts suggests a team spending a lot of time in the neutral zone.
Event rate had a statistically significant negative relationship to both Fenwick Close % (OR = 0.591) and win percentage (OR = 0.896).
So what does all of this mean? First of all, it means that the pace of a team’s game is meaningful in determining whether or not they’ll be successful.
teams playing firewagon hockey are consistently less likely to win than more conservative teams.
a high-event style means your defense is going to leak goals in a big way.
high-event teams have tended to be poor possession clubs as well,
Teams playing a consistently low-event style are those that play effectively in the neutral zone, which is likely to show up in their shooting differential as well.
At the end of the day, all this means that the conventional wisdom on firewagon hockey holds at least some water. If you want to win in the NHL, you need to be able to slow things down.
DON’T SACRIFICE POSSESSION CHASING SHOT QUALITY
shooting percentage varies inversely with shot differential.
the correlation between shooting percentage and shot differential diminished greatly when he focused on tie-game situations.
5-on-5 shooting percentage explains only 5.5% of the variation in even-strength shot differential; in tied situations, it explains less than 1%
The conclusion these analyses suggest is that, apart from what we’d expect to see from score effects, the relationship between shooting percentage and shot differential is indistinguishable from random error.
even if you can trade off puck possession for shooting percentage, it’s not a good idea.
improved shooting percentages benefit weak possession teams less than strong possession squads.
essentially, most of what we think of as “high-percentage shooting” is some combination of lucky breaks and score effects in action.
even if a team could play such a system, it might not be a good idea. You might not be able to win games without “burying your chances”, but you probably aren’t going to the playoffs if you can’t control the puck with any consistency
THE SIGNAL AND THE NOISE
Whether teams can effectively trade off puck possession for higher-quality scoring chances, which would lead to consistently higher Sh%.
shooting percentage is a consistent predictor of teams’ future goals-for ratios;
the predictive quality of Sh% is all over the place.
FIREWAGON HOCKEY II
As such, I sometimes wonder whether there’s a way of identifying teams that are likely to see dramatic fluctuations in their possession play,
Answering this question would be valuable to teams attempting to build for sustainable success.
Specifically, are high-event, “firewagon” teams more likely to see their Fenwick Close fluctuate from season to season than trapping teams?
possession results are more volatile for teams that struggle to play effectively in the neutral zone. This is supported by my earlier work with event rates, which found a significant negative correlation between event rate and puck possession.
generally speaking, the season-to-season pattern in possession numbers is more volatile for firewagon teams.
In general, I think the above results provide equivocal support for my hypothesis that low-event teams are more consistent. High-event teams with strong possession numbers appear more likely to decline than stronger low-event teams,
Firewagon hockey may be riskier, but it does appear to provide a way for poor Fenwick teams to improve their possession game.
QUALITY JUST AS IMPORTANT AS QUANTITY
We care about Corsi% because it predicts future goals for/against better than just using goals for/against when sample sizes are not sufficiently large.
Luck will mostly impact goaltending (save percentage) and shot quality (shooting percentage)
One can conclude that when it comes to scoring goals at the team level shooting percentages is pretty close to being equally important as shot generation
If one did a similar study at the player ‘on-ice’ level you will find the difference in the best shooting percentage players and worst shooting percentage players are significantly more important than the difference in shot generation.
Shot-based metrics are OK to use only when we don’t have a very large sample size. The thing is, this isn’t true for most players/teams.
Hockey analytics has over-hyped the importance of corsi at the expense of other important factors and that is unfortunate.
TWO GRAPHS TO CONVINCE YOU ON SH% - QUALITY = QUANTITY
The problem with shooting percentage is that it suffers from small sample size issues. Over small sample sizes it often gets dominated by randomness (I prefer the term randomness to luck) but the question I have always had is, if we remove randomness from the equation, how important of a skill is shooting percentage?
Well, a 90th percentile CF20 player produces about 25% more shots attempts than a 10th percentile player and a one standard deviation above average CF20 player produces about 18.5% more than a one standard deviation below average CF20 player (over 5 years). Both of these are well below (almost half of) the 45% and 33% we saw for shooting percentage
In summary, generating shots matter, but capitalizing on them matters as much or more.
RELATIONSHIP BETWEEN POSSESSION AMD SHOT QUALITY
is there any relationship between possession and shooting percentage?
While there seems to be some correlation it really isn’t all that significant.
So, it appears that the teams that break the trend of good CSh% equals poor CF% and poor CSh% equals good CF% are the truly good or truly bad teams or, for better terminology, we could call them outlier teams.
Removing the outliers, we see that for a large number of non-elite, non-terrible teams there is a strong negative correlation between possession and shooting percentage such that the difference between a 45% and a 55% possession team is 1.22% hit to CSh%.
From all this, one could infer that an increase in shot attempts correlates with a decrease in shooting percentage.
TRADEOFF BETWEEN CORSI (QUANTITY) AND SH% (QUALITY)
there is generally a strong negative correlation between a teams CF% and shooting percentage.
Better possession teams generally take a hit in terms of shooting percentage.
generally speaking good Corsi teams are weak shooting percentage teams.
All evidence suggests if the Leafs improve their possession game it will come at the cost of shooting percentage. The hope is the improved possession game results in more consistency and provides more benefit than the cost of the hit to shooting percentage
THE DANGERS OF SH% GRAPHS
what the percentages chart does is punish teams for scoring and preventing excess goals.
Goal scoring and preventing is a function of shot rates and shooting percentages. Rather than look at whether percentages might regress, look at the metric we know to be decently stable and a good predictor of success. Shot quality matters, but we know it matters far less than shot rates, and therefore — at least this early in the season — shot rates are the best quick way to examine a team’s start.
CAN ACCURACY BE COACHED
NHL coaches have shown no ability to affect how skilled their teams are at putting shots on net.
None of them are able to actually influence how likely their players are to hit the net despite putting importance on this part of the game.
The best coaches are better at driving shot differential (Corsi or any other shot differential measure) with their systems, but once a shot is taken, all bets are off.
Better shooters tend to take more shots from lower-percentage areas (thereby getting more of them blocked) and aiming for smaller targets (and sometimes missing the net). Considering that shot attempt volume is the best predictor of future scoring, and that NHL goalies save over 91% of shots on net, this is a perfectly fine strategy for a shooter to adopt.
If the shot misses or gets blocked, no problem. It’s as simple as getting the puck back and trying again – that’s the repeatable skill worth developing.
SHOT QUALITY VS SHOT QUANTITY
(Jan 2016)
Team to team shooting percentages in all situations vary from 10.6-8.8 in the mid to upper range, and 8.8 down to 6.4 in the mid to lower range.
But if the team to team success rates are at only 8-10% at the top, what are the success rates of shots in “High scoring areas” ?
If you look at the high slot, or a medium danger area, as of January 18, at even strength teams were only shooting 3.48% from the high slot. From the high danger areas it was closer to 8%. From out high on the points, a low danger area? A whopping 1.58%
Overall it is really hard to find a repeatable kind of success when asked the question of what matters. Is it where you shoot from or how often you shoot?
It is hard to say which approach is better. Try to fight through the great defensive systems of the NHL and get better quality shots? Or simply throw buckets of spaghetti at the wall from everywhere all the time at hope they go in.
ARE WE PREDICTING THE FUTURE OR ANALYZING THE PAST
Top players sh% regressed towards 9.7% while bottom tier players regressed towards ~6.3%
A shooting percent range of 6.3% to 9.7% is substantial. It means good on-ice shooting percentage players would score >50% more goals than poor on-ice shooting percentage players on an equal number of shots.
When it comes to goal production, shooting percentage matters as much or more than shot rate.
Simply looking at long-term on-ice shooting percentages showed that high on-ice shooting percentages were associated with high end offensive forwards and poor on-ice shooting percentages were associated with 3rd and 4th line defensive players. This structure doesn’t result from randomness.
TAKING A PROPER SHOT VOLUME APPROACH
(January 2019)
If you’re going to preach a shot-volume approach, there are a few things you need to do well to be successful – recover rebounds, screen goalies and get sticks on incoming shots, because the odds of scoring on clean shots from outside the slot are less than 5 percent.
Whether it’s even-strength or the powerplay, the most successful offensive teams in the league create as many scoring chances as possible.
It seems simple but it’s clear the Panthers believe their antiquated, volume-heavy approach is the right one.
It’s not.
SHOT QUANTITY OR SHOT QUALITY
(Sept 18, 2020)
Research has shown that save percentage + shooting percentage (PDO) are much more important than the shot differential (difference in shots) in correlating with wins.
Factors In Winning:
1. Puck possession time
2. Save percentage
3. Shooting percentage
4. Team with fewer penalties
5. The team with more faceoff wins
6. Shot differential
7. The team with more hits
For every point shot there is about 1-3% chance of scoring compared to 5-15% inside of the “house”.
Increasing shot quality is the most important factor when increasing goal scoring.
Adding quality is more important than adding quantity.
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