The Toronto Maple Leafs have played a little over half their season, so that means it’s time to look into their results a little deeper.
This was written after game 42, and includes data as of December 5. All numbers are either the Score and Venue Adjusted five-on-five from Natural Stat Trick or, in the case of anything with expected in its name, the unadjusted five-on-five numbers from Corsica Hockey.
Corsi: All shots, whether they hit the net, miss, or are blocked. sometimes called shot attempts. I will use the word shot or shot differential to mean Corsi. I am never talking about Shots on Goal.
Fenwick: All shots that aren’t blocked.
Expected Goals: A shot quality measure calculated by weighting Fenwick by shot location and type as well as other factors, depending on the model used. I am using Corsica’s. xGF/60, for example, is the number of goals per 60 minutes you should expect with average shooters an goalies from shots of the type taken.
Fenwick Save and Shooting Percentage: Just like the Sv% and Sh% you’re used to, only taken as a percentage of all unblocked shots instead of Shots on Goal.
Corsi Then and Now
The charts are a little more complex now, with some past years for reference, the season to date and the two quarters of the season so far. We’ll walk through each one to see if there’s anything to learn from each.
What we should notice first is that the lighter blue bar, the Corsi For percentage, has barely changed all year. To date, it’s just below 50 per cent, and the second quarter is lower than the first. And if you look back in time, you will see that the highest it’s ever been is 51 per cent and the lowest is this quarter which is 49.5 per cent.
The way that 50 per cent shot differential has been achieved has varied. The second quarter shows an increase in both the rate of shots for (CF/60) and shots against (CA/60). This is a fairly dramatic increase on both sides of the ice. Worryingly, the CA/60 was 61 over the second quarter, which was the sixth worst in the league. But the CF/60, which had stagnated in the first quarter to a troubling degree has shot right up to tenth best for the second quarter.
The Leafs were a high event team, for good and ill, in their second quarter. The year to date results are middling, and the Leafs are stubbornly sticking at 17th in the league in Corsi For percentage on the season.
Shots, Expectations and Real Goals
Try to remember this as you look over the rest of the charts:
You should think of Expected Goals information as a kind of grey average baseline to compare actual results to. Actual goals scored come about because of skill, luck, random factors beyond imagining, and the actions of all players on the ice. The reason we don’t predict future success based on past goal scoring is because it’s got too much stuff in it you can’t count on. Shots have more skill and good systems in them, and less of the other stuff.
The first thing we should see here is that the grey bar, the Expected Goals percentage, is even more static over the last two seasons than the Corsi For percentage. You have to go back to the tank year to see it below 50 per cent.
The big swing is in the red bar, the Goals For percentage, and it was great in the first quarter and a touch below expected in the second. The overall season to date is still good and still showing results exceeding average expectations, which is what we want. They just aren’t as glorious as in those first 21 games.
So why is that?
Goalies and Goals Against
Goals For or Expected Goals For has two sides to it, the scoring and the goaltending/defence. First, we’ll look at the goalies’ results.
I’m using Fenwick Save percentage, which is the percentage of unblocked shots saved, and I’m comparing it to Expected Fenwick Save percentage, which is the percentage of the unblocked shots faced that a league average goalie would save based on shot quality. Better than expected means the goalie was good.
First, notice that the vertical axis starts at 90, which is about where the worst starter might sit. The differences are not large between just under 94 and just over 95, but they are surprising in some ways.
To date, the Leafs goalies are just a touch over expectation, and I imagine we could say why without the two other sets of bars to the right. The goaltending was bad, now it’s not, and we see that clearly.
What is a surprise is that from the first quarter to the second the Expected Fenwick Save percentage has gone up by almost one point. That heavily implies that the job of the Leafs goalies got easier because the defensive execution of the Leafs/offensive execution of their opponents changed. What it strongly implies is that the Leafs played well defensively in the second quarter. That seems to contradict that big rise in rate of shots against allowed in that quarter.
Shots that are Lucky and Shots that are Good
Talking shooting percentages is never rewarding. People just don’t like the idea that a lot of shooting is random chance. If a guy is scoring, we like to see it as his skill on display. And it is. It’s just never all skill.
Expected Fenwick Shooting Percentage is just like the save percentage version only taken from the offensive point of view. This is the league average shooter making the shots the Leafs made in grey, while the blue bars are what the Leafs have actually achieved in goals out of all unblocked shots.
I love this chart. Just look at the first three sets of bars and note the stepping up of grey expectation first. That’s an increase in tactical ability, execution and player skill. From tank to wildcard to this year, the Leafs have continually stepped that up as their Corsi For percentage remained basically the same.
This is the bad team/good coach lesson, where you can get decent Corsi results with mediocre to bad players and fool people into thinking you’re good. Then you start to see what better players bring. And then in this year we see the growth in both the team and individuals. That is improvement in offensive structure and player skill.
Now the blue. The blue shows actual results, and you see the luck and the individual shooting skill all mixed in a big ball. In the tank year, the skill wasn’t there. In the wildcard year shooting skill had grown almost to meet the structure underneath it. And this year? The Leafs are outperforming their even better expected shooting results.
The Leafs are a better team offensively.
Now, let’s look at this wild fluctuation from the first quarter to the second. Obviously the results were wildly unsustainable in the first quarter, and the second has been a bit of an over-correction. This is also, by happenstance, completely opposite to the wild fluctuation in goaltending results. Because the Leafs aren’t scoring now, when this did before, they must be bad now, right?
Well, no. The early results were juiced on luck, the latest is what snakebit looks like on a graph. But it’s hard to convince yourself of that while you watch. The goalies are better now, but also getting an easier job. It’s tempting to claim it’s all Freddie Andersen being a star. Or that the lack of scoring is all someone’s fault.
Where the shooting percentage will go next is up to the hockey gods, but the really interesting thing is the drop in Expected Fenwick Shooting percentage at a time when the overall shots for when way up.
Why would that happen? One explanation might be that the Leafs met better defence in this part of the season than they did in the first bit. Another might be that they achieved that pace increase by shooting the puck in more from the point. And I have not looked for data on that, but overall the Leafs have a very short shot distance, and their defenders don’t shoot much. But that may have changed a bit. One other simple possibility is that Auston Matthews, Nazem Kadri and Nikita Zaitsev missed a lot of games in the second quarter, and they all contribute to the usual level of offensive quality.
Conclusion: Is this glass half full or half empty?
How you feel about a team while you watch them often has very little to do with the deeper reality of the team’s quality. What you experience is results over expectation, just like in those charts up there, but your expectations are a lot less mathematical. That’s why the game is fun and also why it’s heartbreaking.
In the first part of the season, before Babcock wrecked everything as some would have it, the Leafs had a rocking high shooting percentage and trash goaltending. They looked great except when Frederik Andersen just refused to make the simplest saves, and it all seemed like it would be a glorious year of punking all comers as soon as he smartened up.
And then the shooting percentage nosedived, and so what if the goalie is good? Losing 2-1 is no damn fun.
So what story do the numbers tell? They say the Leafs have improved in offensive skill and execution over last year. They say the goaltending has stabilized at above expectation on the highest shots on goal volume for a single goalie in the league. They say the Leafs are still mediocre at driving play, better at having the lion’s share of good chances and better still at scoring the most. The numbers also hint at defensive improvement. The Leafs will have to implode in the most dramatic way ever to miss the playoffs now.
How you feel about that depends on where you’d set the bar for the team this year.
And the future? Well the predictive ability of Corsi For percentage says the Leafs will likely keep averaging around 50-50. Barring injuries, it’s unlikely that the team plays worse in any meaningful way, and there’s still two very important players in Mitch Marner and William Nylander who are snakebit on shooting percentage and will someday regress. There is no due date on that, however.
Last time I called the Leafs a premium quality glass cannon. And when I saw this chart below, and the move by the Leafs deeper into “FUN” territory, I’d now say they’ve upped the quality of the glass a little, while eschewing these crazy ideas out there to make your house out of brick or something. That’s for Boston and Tampa, not the Leafs. At least not so far.
Behold! Squiggles!— Micah Blake McCurdy (@IneffectiveMath) January 5, 2018
5v5 unblocked shot rates this year. Team name is the last 25 games of the season. Tail of arrow is the first 25 games of the season.
Winnipeg, my word. pic.twitter.com/r08aYmA5uW
Note: this chart is Fenwick, not Corsi, and the Leafs’ Fenwick is below 50 per cent and has been all year. They aren’t a big shot-blocking team and are one of the teams with the largest difference between their Corsi numbers and their Fenwick. I’m not sure it means a whole lot, given the high Expected Fenwick Save percentage.
Anyway enough math. If you can’t beat them, join them. All aboard for Funtime.