IMPORTANCE OF QoC
(July 20, 2010)
Qualcomp explains 55% of the change in player’s Fenwick results that is unaccounted for by luck.
Linemate quality is obviously going to account for a big chunk of the remainder,
Players in qualcomp change will, collectively, see their Fenwick results (or scoring chance results if we have them) move the same direction as their quality of competition. Nothing can stop it (in other words, the better competition, the better your Fenwick).
Higher QUALCOMP results in MORE scoring!
So by and large, the tougher your competition the more you’ll score
DOES QUALCOMP MATTER
There's no correlative relationship between a player's Corsi and his QoC
FURTHER TO DOES QUALCOMP MATTER
Is Quality of Competition (aka Qualcomp) a significant statistical indicator in driving an individual player’s Corsi number
The answer is a bit convoluted, but I’d argue that it is.
overall, the effect is roughly what we’d expect – the tougher your ice time, the worse your results.
IMPORTANCE OF QoC/QoT
(Jan 2012)
There is very little variation in quality of opposition, almost to the point we can almost ignore it. The variation in quality of teammate is significant and cannot be ignored
the quality of opposition has very little variation across a group of players almost to the point that it can be ignored.
quality of competition a player faces varies very little from player to player and we should be really careful when we use arguments such as “Player A faces tougher quality of competition” because in the grand scheme of things, the quality of competition probably only has a very minor influence on Player A’s on-ice stats.
MORE ON IMPORTANCE OF QoC
It has been widely presumed that the difficulty arises from stratification of playing time; if the players who face top competition are usually themselves good players, then we would not see facing top competition correlating with poor results
The most common things to look at when evaluating a player’s usage are the quality of his teammates, the quality of his competition, and how often he started in the offensive or defensive zone.
Attempts to correct for the strength of a player’s teammates are also common. For example, rather than look at Corsi shot differential, we will look at a player’s relative Corsi: the difference between the team’s shot differential when he is on the ice and when he is off the ice. By asking how much better his team did when the player was on the ice, we remove some of the teammate effects and hope to get closer to understanding which players are the best and worst on a given team.
It is clear that quality of competition is an important aspect of context, that players do substantially better in their shifts against weaker opponents. However, it is still an open question whether this is something we can and should correct for at the season level – does anyone face competition that is consistently strong (or weak) enough that we need to correct for it?
How big are differences of usage?We know that coaches manipulate ice time to get certain matchups. This results in real, persistent differences between players in the competition metrics; the one based on relative Corsi is particularly effective at identifying which players the coach tries to use against the opponent’s top line.
Everyone faces opponents with both good and bad shot differential, and the differences in time spent against various strength opponents by these metrics are minimal.
Now we see why it has proven so difficult to apply a correction factor based on competition faced: to a first approximation, everyone is facing more or less the same competition by these metrics.
While competition certainly does play a big factor in determining how a player will do in any given shift, with these competition metrics we see nobody with usage extreme enough to require a major correction factor.
The analogous situation in zone starts would be if everyone’s offensive zone start percentage were between 48% and 52%; such small corrections are scarcely worth the effort, and a person who ignored competition when evaluating players would not be wrong by much. Quality of competition is very similar to shot quality: it plays a huge role in individual shifts/shots, but over the course of a season the differences across teams and players are small enough that it can usually be neglected.
EFFECT OF TEAMMATES & OPPONENTS
Immediately, we are seeing how a player’s teammates have a far greater impact on a players Corsi For per 20 minutes than a player’s opponents.
Differences in Quality of competition amongst players are not large enough to have that great of an impact.
It seems that for at least defensemen, the defensive side of the game is far more reliant on teammates than for offense.
teammates have a far greater effect on player performance than a player’s opponents.
Teammates have a greater effect than opponents. But for forwards, Teammates and Opponents are explaining far less variance for CF20 than for defensemen.
One is that quality of teammates is far more important than quality of competition, and thus when we look to evaluate players we should focus more on who they played with rather than who they played against.
Second is that Defensive performance is affected far more by teammates and even opponents than offensive performance.
DOES MATCHING COMPETITION MATTER
Competition, on a possession level, is pretty much a zero sum game in hockey.
Why? Because if your worst line is facing the opponents’ best line, your best line is facing the opponents’ weaker lines!
On a possession level, competition is thus a zero-sum game. That doesn’t mean it totally doesn’t matter – what it therefore can do is change the pace of a game.
It should be noted that teams show VERY LIMITED ability to match lines throughout a game and particularly over a season, which is why competition barely moves the needle for individual players long term.
That said, it’s more likely for there to be offensive or defensive zone specialists – people better in one zone than another – than competition specialists (people particularly better against top competition than bottom comp?), so it’s not quite as zero sum as competition.
In short, line matching is for the most part a zero-sum game. Don’t get too obsessed with it.
QoC & QoT ARE NOT SIMPLE
We know that linemates have a larger impact on results than competition on the average
a 1 percentage point change in teammate and competition Corsi% has an equal but opposite impact on observed output
As one would guess, playing against a tougher opponent reduces the observed result one should expect.
We do not see the impact being quite the same for linemates as it is for line matching and competition.
We see here that an increase of 1 percentage point in teammate Corsi% has an equal but opposite impact (+1.5) in observed results as competition Corsi% (-1.5). The distribution of teammate Corsi% in the NHL is greater than competition Corsi%.
Your teammates, especially most common linemates, will impact your results more than how your coach tends to line match you. No matter how much a coach tries, there are still changes on the fly and the opposing coach muddying the line matching.
RELATIONSHIP BETWEEN COMPETITION & RESULTS
It is apparent that the quality of competition has a similar effect on observed results no matter the quality of the player under observation.
This effect is independent of the skill of the player under observation.
We have shown that the Quality of Competition has a constant direct impact on the observed CF% of players at all skill levels.
The point is that Quality of Competition does matter and is important in some cases. We may have been too quick to discount its impact simply because over time, the effects are washed out. But this should not preclude the use of QoC adjustments when analyzing player performance over short periods
DISTRIBUTION OF QoC/QoT
I did not find evidence that coaches can choose the quality of competition their players face over a full season of play.
quality of teammate effects are observable in a full season sample size. We can see differences in the quality of players’ teammates.
The quality of opponents a player faces are too widely distributed for any quality of competition effects to shine through in a full season.
The effects of a player’s teammates do not wash out over the course of a season.
In a single game or a playoff series, quality of competition can probably be said to have a greater impact than it would over a full season
QoC – HUNWICK VS MARINCIN
Current research has suggested that it doesn’t move the needle very much because the range of competition is small and that quality of teammates trumps its effect. I think the latter is mostly true, but the former isn’t and it’s because of how it’s measured.
Which begs the question, how much does this actually matter?
Still, any effect should likely be accounted for in some way even if they’re all tiny. It’s sort of like a hockey version of death by a thousand cuts: extreme zone starts may have a small effect, extreme competition may have a small effect, poor teammates may have a small effect, but all three at once might have a bigger effect combined than we might realize.
The big thing is we shouldn’t dismiss the five guys skating in different colours. They matter. Yes, who you play with will generally be more consistent and have a larger effect than who you play against, but both should be accounted for in some way. It’s likely that the two affect different players in different ways
HOW IMPORTANT IS QoC
Both Quality of Competition and Quality of Teammates matter. They also don’t matter. It depends on the position and metric you’re looking at.
A forward’s Fwd QoC, Fwd QoT, Def QoC, and Def QoT, while controlling for team effects, will explain 69% of his shot rates for.
We see the bulk of the significance is due to the defensemen he plays against (Def TOI QoC) and the forwards he plays with (Fwd TOI QoT). They appear equal in importance. The defenders he plays with and the forwards he plays against do not appear to have much significance.
When looking at a forward’s shot suppression, the forwards he plays with and plays against appear to be the significant factors.
When explaining a forward’s CF60, the QoC of the defensemen they face appears to matter slightly more than who the QoT of the forwards they played with.
For defensemen, there was only one metric of significance for both offense and defense. Def TOI QoT for CF60 and Fwd TOI QoC for CA60.
Much of this is logical as well: for forwards trying to create offense, the defensemen they are matched up against will have an impact.
QoC DOESN’T MATTER TO ANALYSTS
(Aug 2018)
Here’s the issue: most hockey analysts have come to the conclusion that Quality of Competition doesn’t matter anywhere near as much as people think it does.
“It matters, on average, about three or four times less than quality of teammates does,”
Analysts downplay the importance of Quality of Competition for several reasons. One of the biggest is that its impact is so much smaller than the impact of Quality of Teammates.
Since Quality of Teammates varies more than Quality of Competition between players, the effect of the strength of your teammates will be stronger.
“It turns out that the two main things that are considered ‘tough’ usage – defensive zone starts and playing against tough competition – happen at the same time very often,”
Essentially, if you take into account a player’s zone starts, you’ve already accounted for most of the effect of Quality of Competition. If you weight both factors equally, you’re at risk of double counting.
Quality of Competition just isn’t that important. Or, to put it another way, it’s not that Quality of Competition doesn’t matter; it’s just that other factors matter a lot more.
On a micro level — looking at a single shift, a single game, or even a few games in a row — of course Quality of Competition matters. We can see it with our eyes and we can see it in the numbers.
On a macro level — over the course of a full season or across multiple seasons — the effects of Quality of Competition fade.
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