Photo Credit: Fred Kfoury III/Icon Sportswire via Getty Images)

By: Lydia Murray | Follow Me on Twitter @lydia_murray12

Over the course of the past month or so, I’ve published articles using shot heatmaps on the Bruins offense, defense, and power play during the regular season. Now, it’s time to take a look at the penalty kill. In addition to breaking down how it was in the regular season, I’m going to discuss how it seems to be in the playoffs. I do not have a heatmap to go off of from that, so it’ll purely be my observations, so keep that in mind. Now, let’s get into how these things work. Please note, the next two sections are taken directly from the previous three articles. If you have already read them and/or just know how heatmaps work, feel free to skip ahead! But, for those of you haven’t or that just need a refresher, let’s dig right in!

A Short Introduction to Shot Heatmaps

Before I begin, here’s a short overview of how to read these heatmaps for those of you who don’t know or need a refresher. This is just a basic overview of how these heatmaps work. If you want to see a really in-depth analysis, you can check one out (albeit of the San Jose Sharks) here. But anyway, these maps illustrate the number of unblocked shots (not necessarily on goal) for or against a team compared to the league average, and where those shots are coming from. Blue means that fewer unblocked shots are generated from a given spot than the league average, whereas red means more are generated than the league average. The deeper the color, the further away from the league average a team is from that spot. White means that shots are being generated at the league average from that particular spot. 

With this in mind, on offensive graphs, blue is good, and red is bad. Obviously, you want your team to be generating a ton of shots, and ideally, they’ll be producing more than most other teams. On the other hand, for defensive graphs, the opposite is true. When an area is blue, it means that team is letting less unblocked shots through than the league average. It goes without saying that’s a great thing. The fewer shots that get through unblocked, the fewer chances an opponent gets to score. 

Defining Areas of the Ice

Before I get started with the actual heatmaps, there’s just a few more things I want to go over. The picture in the embedded tweet above is an example of the heatmaps you’ll see in this article as it was directly on the website. This is great on its own, but I decided to add a few more things to aid in my analysis.

As you can see, I’ve added a box and a trapezoid to the above graph (as well as made the crease more obvious). My apologies for the subpar photo editing job, I don’t have access to the best software and I’m not too skilled at it either. But, it’s good enough for the purposes of this article. Please note, these outlines may be off a little bit, but if they are, it’s not by much as I was as exact as possible with the tools I had. 

I’ve added these areas to aid in my analysis of these graphs. The box area I have outlined is known as the “slot”, and shots from this area are considered “high danger”. The trapezoid is known as just that, and shots from that area are considered “medium danger”. Shots from anywhere else on the ice are considered “low danger.” According to this article, in the high danger area, shots have at least a 10% chance of going in. The article also says that shots from the medium danger area have a 3-10% chance of going in, while low danger shots have at most a 3% chance of going in. 

To be clear, those percentages are averages, as some shots obviously stand a better chance of going in than others, even from within those areas. For example, a shot from the backdoor of the net that’s wide open has a much better shot than one that’s coming from right out front with the goalie square to it. But anyway, with all of that out of the way now, let’s get into the actual analysis these things.

Now, Onto the Analysis

Both Circles and the Right Point Were Great

As you can see from the graph, the Bruins did an excellent job suppressing shots from the right side of the ice during the regular season. Let’s start with the right circle. There isn’t a single spot in it where they allowed more shots per hour on while on the PK than a league average team, which is outstanding. In fact, they allowed between 0.6 and 1.0 less shots per hour than the average team for the most dangerous areas of it. Considering there aren’t many spots per power play and there usually aren’t too many power plays per game, that’s incredible. 

The Bruins also did a good job of suppressing shots from the right point (and the whole right side really). They allowed around 0.1 and 0.3 less shots per hour from that point than the average team, which is great. This is especially true considering they had two large areas of ice where they were even further above league average than that (more on the second one shortly). It’s a good sign that the Bruins were good at suppressing shots from at least one point, as even though they are technically low-danger shots, they often produce large rebounds that other players can scoop up and bury, or the goalie is screened when they’re coming through. So, a shot from there is more dangerous than it appears, because rebounds are the most common way goals are scored in the NHL.

The left circle was good too, but not quite as good. The Bruins allowed between 0.3 and 1.0 shots per hour less than a league-average team for the most dangerous area of the circle, which is great. But, for the far left part of the circle, they allowed between 0.3-1.0 more shots per hour than the average team. However, that isn’t a very dangerous part of the ice, as it’s a weird angle to the net. So, while it’s far from ideal to be below league average in a spot, it’s not too detrimental to be from a spot like that. It’s not realistic to say that they’ll be above average in every area of the ice, and if there’s going to be a spot where they aren’t as good, that’s a good one to pick.

The High Slot Was in Need of Work, Slot Was Okay But Could’ve Used Some Too

The biggest area of the ice the Bruins needed to be better about protecting on the PK was the high slot. The high slot is considered to be one of the most dangerous areas of the ice, and the fact that the Bruins allowed between 0.6-1.0 shots per hour more than an average team form that area is not good. It obviously wasn’t too detrimental to them, as their penalty kill was third in the league with an 84.3% success rate. But, that’s not a recipe for success usually. Luckily, they appear to have cleaned it up for the playoffs, so let’s hope that continues for the rest of their postseason and then carries over into next year.

The slot area of the ice also could’ve used some work. It was nowhere near as bad as the high slot was, but it still wasn’t great. It’s considered to be the most dangerous area of the ice, so to have any spots in it where they were allowing more than the league average in shots is not exactly good. This is especially true given the main area of the slot they were allowing more than the average number of shots from was right at the top of the crease, which is the most dangerous part of it. They were allowing between 0.1 and 0.3 more shots per hour than the average team from one area there, which is far from ideal. Granted, you can’t really block shots from that area, but you can prevent them from happening, which is what the Bruins needed to do more of.

That being said, the Bruins had some spots of the slot where they were allowed less than the league average amount of shots. The biggest spot of the slot where they were below average is the left edge of the crease, which is a very dangerous area. They allowed between 0.6 and 0.8 fewer shots per hour for most of this area, which is incredible, especially considering I’ve already talked about a few spots where they were even better than that. There really aren’t many shots on a power play usually, and there normally aren’t too many power plays per game, so for the Bruins to have been that strong in as many areas of the ice as they were is amazing.

The Middle of the Blue Line Also Needed Some Work

The only other area of the ice that the Bruins could’ve stood to work on allowing fewer shots from was below the middle of the blue line. They were allowing between 0.3 and 1.0 more shots per hour than the average team from most of that area. Even though that is a low-danger spots for initial shots, like the points, it’s still a dangerous spot of the ice. Most goals in the NHL are scored off of rebounds, and shots from that far out usually produce big rebounds as they’re hard for goaltenders to control. They’re also usually screened and so don’t know they’re coming until they hit them. So, it was not ideal for the Bruins to be that far below league average from that spot.

How Does This Compare to the Bruins PK in the Playoffs?

As I said earlier, I don’t have a heatmap of how the Bruins PK has been in the playoffs. However, I wanted to take some time and compare it to how it was during the regular season using what I personally have noticed. For the most part, I think it’s been very similar. They have an 81.1% success rate in the playoffs, so that’s pretty close to their 84.3% success rate in the regular season. They’re also fairly similar in where the shots were mostly coming from what I’ve noticed. 

The only spots I’ve really been noticing a difference are the high slot and the right point. I’ve noticed a lot fewer shots being taken from the high slot by opponents while the Bruins are on the PK, which is excellent. However, I’ve noticed more shots are getting through from the right point, especially in their current series against the Lightning. Unfortunately, I’ve noticed this for bad reasons, as a lot of the PP goals that have been scored by the Lightning this series were off shots originating from that spot off the stick of Victor Hedman. It’s an area they will definitely want to clean up tonight by blocking more of those shots or making sure Hedman can never get them off. 

But, other than that, I think the PK has done a similarly good job in the playoffs as they did in the regular season, with the notable exception of the disastrous Game 3 against the Lightning. In fact, I could even argue it’s been better, and that Game 3’s performance brought the percentage down significantly because it did. However, at the very least. I’m confident that it’s been just as good, as they got better at one spot but worse at another, while staying largely the same in the others as near as I can tell. The spot they improved upon was statistically a medium-danger one, which is great, but to get worse from one of the points isn’t exactly great because rebounds and screens arguably make those shots even more dangerous, although in an indirect way.


In short, the Bruins did an excellent job suppressing shots from the circles and the right point during the regular season. They needed to improve in the high slot and the middle of the blue line, but other than that they were pretty good. The slot itself could’ve used a little work too, but overall it was ok. They’ve done a similarly good job on the PK in the playoffs, and possibly even a better one when you take out Game 3 against the Lightning.

As for where those shots are mainly coming from during the playoffs, they’re from most of the same spots as they were during the regular season. However, they appear to have improved in the high slot while getting worse at the right point. But, overall, the Bruins have been excellent on the PK during the playoffs, just like they were during the regular season. Here’s hoping they have a great night on it tonight and stay out of the box for the most part. If they can do that, I’ll think they’ll live to see another day in the bubble.

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