When it comes to goal prevention in hockey, we can essentially split it into two parts: skater defence and goaltending. In terms of defending, the responsibility of the skaters is to limit scoring chances for the opposition as much as possible, while the job of the goaltenders is to stop the shots that do get through.
However, when a team allows a high number of goals against, there always seems to be endless debate regarding whether the team defence or goaltending is the primary culprit for those results. In my experience, I feel many people struggle to separate the two objectively.
This is what is currently happening with the Oilers.
For yet another season, Edmonton has had a somewhat underwhelming start to the year, and once again, a long-standing question is asked: are the Edmonton Oilers good enough defensively?
So far, the Oilers rank 20th in the league in goals allowed per hour, which is unsatisfactory for a Stanley Cup contender. To address this issue, it seems that Edmonton’s management is leaning towards acquiring a defenceman over a goalie at the current moment. Per OilersNow host Bob Stauffer, Edmonton may be pursuing a top-four defenceman who can play the right side, while according to NHL insider Pierre LeBrun, the Oilers are going to “sink or swim” with Stuart Skinner, Edmonton’s starting goaltender.
This certainly does make sense, as Edmonton’s right-defenceman depth is a massive weak point after Evan Bouchard. They have also played the likes of Troy Stecher and Travis Dermott in the lineup consistently, who are more suited to be 7th or 8th defencemen on a contender.
But what if I told you that Edmonton’s overall team defence has been quite fine, if not very good?
My go-to statistic for evaluating team defence, separate from goaltending, is expected goals against. This metric has a controversial reputation among fans, but it’s not as overly complex of a stat as some assume.
In a way, expected goals can also be called weighted shot attempts. To compute xG, every shot is assigned a specific value based on the quality of the shot and the probability that the shot will result in a goal. For instance, a shot in the inner slot may have an xG value of 0.5, meaning it has a 50% chance of going in, while a weak wrister from the point may have an xG value of 0.01, meaning it has just a 1% chance of going in. The sum of all these values equals the team’s total expected goals. It is not a perfect stat, but I prefer it much more than simple shots for and against, which fail to account for shot quality.
Now, different data sources can have slightly different methods of calculating expected goals, as they have their own models. So to strengthen the accuracy of this analysis, let’s look at how three differently commonly used models rank Edmonton’s skater defence:
All three models comfortably rank Edmonton as a very solid defensive team.
Additionally, Natural Stat Trick has a scoring chance model that separates shots into three categories: low, mid, and high-danger. Using this model, Edmonton has allowed 8.88 high-danger chances per 60 minutes of play, the lowest in the entire league.
On paper, Edmonton’s defensive core certainly has room to improve. But overall, the Oilers have done a very good, if not great job at limiting quality scoring chances against this season. In this aspect, I feel like they are quite underrated.
So, despite their strong chance suppression results, why do the Oilers still rank considerably below average in goal suppression?
I believe the primary answer is goaltending.
Now, I typically try to avoid placing excessive blame on the goaltending, as it is often lazy and superficial analysis to simply scapegoat a goalie for an entire team’s struggles. And, to clarify, that is not what I’m doing here; the team’s lackluster finishing and power-play have also significantly contributed to Edmonton’s disappointing start (topics for another article).
But, specifically regarding goal suppression, the overwhelming body of evidence suggests that it is more of a goaltending issue rather than a defensive one.
To evaluate goaltending, I typically use GSAx – goals saved above expected. I am not a fan of save percentage, as unlike GSAx, raw SV% fails to account for the quality of shots a goaltender faces.
Edmonton’s starting goaltender is Stuart Skinner, who has appeared in 15 games, while their backup is Calvin Pickard, who has appeared in 8. Here is how they rank relative to the league in cumulative GSAx using three commonly used models:
Safe to say, these results are not pretty.
Interestingly, MoneyPuck rates Skinner significantly worse than the other two models and Pickard slightly better, but regardless, all three models combined strongly indicate that Edmonton’s goaltenders have been well below average. As of November 17, TopDownHockey’s model also ranks Skinner dead last in GSAx (-7.7).
What Skinner and Pickard’s GSAx indicates is that with league-average goaltending, the Oilers would roughly allow ~9-11 goals less, which is pretty significant in just 22 games.
To strengthen this analysis, we can also use data from Clear Sight Analytics (CSA) – a proprietary model. This is the type of model that NHL teams often pay thousands of dollars to access.
The biggest flaw with publicly available models, such as the ones mentioned above, is the lack of puck movement data; in simpler terms, public models are primarily reliant on the location of shots to determine quality, as the NHL does not release pre-shot movement details. So for example, public models cannot determine if a pass preceded a shot, if it came off the rush, and so on. As a result, certain teams that allow a high amount of rush chances or shots off dangerous passes can be overrated by public data, while the goaltenders on those teams can be underrated.
However, proprietary models like CSA do incorporate a variety of different pre-shot movement variables, such as passing and situational details of shots (you can view the exact list of the inputs in their model right here). Luckily for us, CSA releases a limited amount of data publicly, such as the top-five and bottom-five teams and goaltenders using their model.
Using CSA’s data, Stuart Skinner ranks dead last in the league in goals saved above expected with a -7.7 GSAx. This roughly matches Natural Stat Trick’s model, which ranked the Oilers as the fourth-best defensive team in the league.
Furthermore, according to Stephen Valiquette as of November 13, who has access to the entire CSA database, Edmonton has allowed the second fewest east/west rush chances over the past two seasons, but Skinner ranks dead last in save percentage on those types of shots.
So, whether you use public data or proprietary models, Edmonton’s team defence ranks quite well, but the goaltending numbers are ugly.
I think what often happens with mediocre goaltending is that it makes the defence look worse than it is at first glance. We could sit down and analyze the faults of the skaters on every goal the Oilers have allowed, but we have to note that every team in the league is going to allow dangerous scoring chances. There is no perfect defensive team, and there never will be.
The reality is that, overall, Edmonton has been fantastic at preventing high-danger chances against, but the goalies tend to allow a very proportionally large amount of high-danger goals against, which can make the team’s HD chance suppression seem worse than it actually is.
Sometimes, you need your goaltender to bail you out, and that has not occurred enough this season.
All things considered, the Oilers should still undoubtedly consider looking at a 2RD upgrade, but the overall team defence is not as big of a concern as it used to be. The emergence of the Darnell Nurse and Brett Kulak pair (which I wrote about last week) may also significantly put less pressure on the team to acquire a top-four defender.
While there aren’t any bonafide starters available, at the very least, the team should consider looking for an upgrade on Calvin Pickard to limit Skinner’s workload and to ensure there’s a more reliable backup option when Skinner struggles. Considering that the current right-defence trade market is quite unimpressive, a goaltending upgrade may end up making a more significant impact than a top-four defender.
As they approach the trade deadline, the Edmonton Oilers should strongly consider exploring the goaltending trade market.
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