The Perceived Value of Blocked Shots

[Editor’s note: This is a guest post from clib542, who has been nerding it up over on Twitter under the same username. I asked him if he wanted to put his findings into a full-fledged article, and here we are!]

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It is no secret that the Calgary Flames are good at blocking shots. There is more to it than just getting in front of the puck; it takes courage and grit. The players who are best at blocking shots are the heart and soul of the team and are often leaders on and off the ice. 

You could argue that there is an art to blocking a shot, involving timing and technique. I think it would be safe to say Bob Hartley expects the players to block shots, and it is used as a defensive strategy. For every shot blocked, it is one fewer shot the goalie needs to save. 

However, is putting yourself in front of a 100mph shot worth it? Every year there are countless injuries due to blocking a shot. Unless a player dives across the crease, or knocks a puck off the goal line, preventing a sure goal, how much value is there in blocking at shot?

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Anatomy of the Shot Block

Not all shot blocks are created equally. Some players get in shooting lanes and take the puck off their skates or shin pads. Others leave the ice to dive in front of the puck, ideally feet first, but players have been known to go head first. Shots can also be blocked by getting a stick in the way to deflect the puck out of play or away from the net (if not into their own goal). 

Some of these techniques are better than others, but I am not going to look at that.

Blocking Shots Stats

Since the beginning of the year, I decided to track the differences in the events after a blocked shot and not blocking the shot (shots on goal and missed shots). To make it simple enough to follow, and the ability to use the – Full Play by Play – Game reports, I separated the events into four categories.

  1. Allowed another shot (shot on goal, missed shot, or another blocked shot)
  2. Stoppage in play (by goalie or puck out of play)
  3. Possession not changed (event happened in defensive zone)
  4. Possession changed (event happened in neutral/offensive zone)

The last two categories are not as important as the first two as there are so many different possibilities. 

Essentially, in the defensive zone, there is a puck battle where either team could come away with the puck. Events in the neutral or offensive zone can be anything from a battle for the puck to an attempted shot by the Flames.

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After 17 games – not including last night’s affair against the Capitals – Flames have blocked 284 shots, and allowed 614 shots towards the net.

After a Blocked Shot After Allowing a Shot
1. Another Shot 35.6% 33.9%
2. Stoppage in Play 21.5% 33.7%
3. Possession not Changed 19.4% 14.7%
4. Possession Changed 23.6% 17.8%

Again, try not to put too much into the bottom two categories because of the many different outcomes. 

The numbers change between blocking a shot and not blocking, but the differences in percentages is both are around 3-4. 

What stands out to me the most is the first category: allowing another shot. According to the numbers, the Flames are slightly better off when they do not block the shot than when they do. Albeit, the difference is very small, but it makes you think if putting an emphasis on blocking shots is worth it. 

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It is too simple just to say 10% of blocked shots would have resulted in goals (based on save percentage), as there is no way in knowing if the original shot would have been on net, as well as other factors impossible to calculate working with hypotheticals.

To compare with the Flames, I also decided to look at a team who is at the bottom of the league in blocking shots. I do not follow New Jersey too closely, but being at the bottom of the league, this probably means their defensive strategy does not start with blocking shots.

After 16 games, Devils have blocked 204 shots, and allowed 573 shots towards the net.

After a Blocked Shot After Allowing a Shot
1. Another Shot 31.4% 26.9%
2. Stoppage in Play 16.2% 33.7%
3. Possession not Changed 24.0% 22.3%
4. Possession Changed 28.4% 17.1%

There are some clear similarities and some clear differences here. When not blocking a shot, both the Flames and the Devils get a whistle 33.7% of the time. While still high, the Devils do a better job not allowing another shot after the original block and are favourably better when allowing the shot through. Granted though the Devils have Cory Schneider and not Karri Ramo starting most of their games, it would appear they allow the goalie to make the save.

In an article in the Boston Globe last year, Tuukka Rask said he would prefer the defense to be in position to clear rebounds or take the man than go down to block the shot. Dougie Hamilton mentioned something similar when talking about the differences between the systems of Boston to Calgary in Elliotte Friedman’s 30 Thoughts

Based on the numbers, it is not hard to support these ideas. I am not saying Flames should stop blocking shots, but to base your defensive strategy around it does not give the team any statistical advantages.

The Dangers of Blocking a Shot

Take a look around the league. Players such as Paul Stastny, Dwight King, and David Pastrnak are all currently injured due to blocking a shot. In recent years, Giordano, Brodie, and Bouma have all lost time because of an injury caused by the puck. Intentionally or not, blocking a shot can result in an injury. When a player is out of position attempts to block a shot, they become even more vulnerable as equipment does not cover all areas of the body. 

Bob Hartley does not seem to be too concerned. In a Calgary Sun article before the season started, Hartley acknowledged the possibility of injury, but implied potentially stopping a goal by blocking a shot was a better option.

Value in Blocking Shots

When it comes to the “eye test”, blocking a shot is right up there. It is a noticeable event, which if everything goes right, saves a goal against – then leads to a goal for. Players are praised by coaches and the media for sacrificing their bodies for the team. Defensemen get labelled as good defenders even though the reason for the high number of blocked shots is because they allow a lot of shots against.

If the purpose of blocking a shot is so your goalie does not have to make a save, it seems meaningless you would employ a strategy which allows more shots after the initial one than if they let the goalie make the original save. Maybe a better strategy would be to get into the shooting lanes to prevent the shot in the first place. 

As much as the Flames goalies are not making the save this year, the team should trust them to do their job. Let the goalie see the puck and clear the rebound if there is one. 

I will continue track the events after a shot for the rest of the season, but the numbers have levelled off in the last couple of games.

  • EhPierre

    I thought the point of this article was to boost Russell’s trade value. If other GMs read this and see that there isn’t much value in blocking shots, how are we suppose to trade Russell?!

    Bad Ari, bad

  • YWC

    Quick thought: advantages for defence strategy based on blocking:
    1. Saves energy when defending.
    2. No overcommittment by the defender leaving less space
    3. Blocked shots may lead to breakaways.

    Note this is theoretical. Also not saying this defensive scheme is without any flaws.

    • clib542

      I think your first two advantages are false. Players like Russell and Bouma often over-commit because they’re going for the blocked shot. And falling down and having to get back up doesn’t save energy at all. It takes a lot less energy to stay on your feet. At best, shot blocking wastes just as much energy as not blocking shots.

      • YWC

        Sorry should have added that I was writing more about the defensive scheme we employ that focuses on shot blocking.

        If you look at Flame’s defensive system (more so for last year), Flame’s defenders would stay at their position rather than pressuring the opposition with the puck in order to take away any shooting lane.

        By not pressuring as much, defenders would conserve energy and if there is an opportunity, will rush out for a counter offensive.

  • Crazy Flames

    I don’t think there is any question in the value or perceived value of blocked shots. When done effectively blocking shots is the difference between winning the cup and not. Go back and watch some playoff hockey and tell me blocking shots is not invaluable.

    The problem with them Flames it they rely heavily on blocking shots. That is because they give up too many shots and good chances as is. If they were a better team (ie the Kings) and didn’t give up as many shots and scoring chances any blocked shot would frustrate the opposing team to no end.

    Be interesting to see your numbers on more effective teams then Calgary and New Jersey

    • piscera.infada

      The point is that blocking shots is not an effective defensive zone strategy in and of itself.

      The problem with them Flames it they rely heavily on blocking shots. That is because they give up too many shots and good chances as is.

      I would actually argue this as more of a “chicken and egg” argument. Why do the Flames give up so many shots and chances? Because the defensive system outside of Brodie and Gio is to fall back and block a shot. Watch Russell play closely. He’ll be in a 1 on 1 situation, and what does he do? The majority of the time, he drifts back into the shooting lane (usually screening the goalie) and then flops on his knees or side. This has two inherent draw backs (aside from screening the goalie): it gives talented (and even not so talented) players coveted time and space, and it opens up additional passing lanes (which, with the additional time and space, are easier to exploit).

      Even the least seasoned Peewee player knows that in 1 on 1 situations you limit the time and space of the player. That usually manifests itself in the old adage: “take the man”.

      When done effectively blocking shots is the difference between winning the cup and not.

      To the earlier points above, no one’s arguing this. They will point out, however, that there is a very pointed difference between Lance Bouma putting his face in front of a clear one timer on the penalty kill, and blocked shots being your defensive system.

      The Kings and Blackhawks have won cups because their defensive system is predicated first and foremost on getting the puck out of the zone–not limiting pucks that go in their net. The funny thing is, generally, when the puck isn’t in your zone, pucks don’t go in your net. When you cede your zone to anyone who wants it, and allow them to take shots, funny things happen–like pucks deflecting off a player’s face and ending up top-corner.

      The issue raised here, is not if there’s inherent value in blocking a puck. It’s a question about using blocking shots as a system. The funny thing is, the Flames have enough plus-skating defensemen that they shouldn’t have to rely on that. If you’re looking for parallels, look at how The Rangers defensive number improved between John “my stars will block all the shots” Tortorella, and Alain “possess the puck and get it out of the zone” Vigneault.

      • clib542

        Exactly.. It’s not about blocking the shot, it’s about the system. If Frolik goes down to block a shot and misses 3-4 weeks due to an injury, was it worth it? Hartley figures that getting injured is part of the game, whether it’s blocking a shot or getting elbowed to the face. Injuries will happen, but I’d suggest no player is looking to put their face in front of a stick. Other than a goal, which happens 5ish times a game, the outcome of blocking a shot and not blocking a shot is similar. With this information, different defensive strategies can be made to 1. Prevent a shot 2. What to do after the shot. If everything else other than a shot is equal, a save and a whistle is a great option as it gives the team a chance to change tired lines. A faceoff is no different than a puck battle in the corner.

    • clib542

      Pick a team and I can look into it. I’m all for getting more information. I was thinking of doing a team who has a good goalie and blocks a lot as well as a team which below average goaltenders and doesn’t block a lot. Let me know

  • The GREAT Walter White

    “[Editor’s note: This is a guest post from clib542, who has been nerding it up over on Twitter under the same username. I asked him if he wanted to put his findings into a full-fledged article, and here we are!]”

    If you need someone to write a full-fledged article about why we should trade Backlund NOW, please let me know Ari……


    • piscera.infada

      F*** off Walter.

      ———-FN MODERATOR: Clean it up. This is an unnecessary commenteven Walter has a right to his opinion. Please don’t reply to trolls, even our own homegrown ones.

  • clib542

    Another point.. How often do you hear about how great a player is at blocking shots at the draft? It’s not something good teams look to fill a need. It’s something a player does to stay in the league. Like fighting, blocking shots has been identified as a skill, when if reality, anyone can do it.

  • Rock

    To block a shot means you have to be in a good defensive position. Would be nice to see stats that shows players on the ice when there is a shot allowed on goal. So if your out of position defensively then it will show. But to say that you are no good cause you block shots is crazy.

    • piscera.infada

      To block a shot means you have to be in a good defensive position

      Sure, it might mean you’re in the right position. But as outlined above, are you making the right play once you’re in that position?

      Again, no one’s saying “if you block shots, you’re no good”. The argument is that “blocking shots is not a viable defensive system”. Blocking a shot is something that logically follows from playing the sport. Is blocking shots the best way of stifling offense though? No, it’s not.

      My prior example of Kris Russell is useful here. First, there can be some argument as to whether standing in front of and screening the goalie (more than he otherwise would be), is in fact “good defensive position”. However, if we grant that to be true, is blocking the shot the “correct defensive play”? Is it more effective for Russell to skate towards the player in possession of the puck and take the body, limiting time and space? Is it more effective for him to limit a passing opportunity? Is it more effective for him to try and angle said player to the boards, and pin him there?

      Sometimes, the answer might be “yes, block the shot”. But usually it isn’t. Ergo, it probably shouldn’t be considered an pillar of defensive play, to say nothing of requisite defensive play.

      • Rock

        By the time a shot block is made other options of defensive plays are over. The one thing that you have not done is over commit to make a shot block. Also if you do shot block you have also had your man covered also. Of course your getting a shot against but never a goal against when you have made a shot block. How could that be bad. It is just important to keep the puck out of your net as it is to score goals. Blocking shots win you hockey games that is a fact

        • piscera.infada

          By the time a shot block is made other options of defensive plays are over.

          The simple fact that the Flames employ a defensive scheme premised on blocking shots (as evidenced by Hartley’s statements on blocking shots), proves that there are, in fact other options available. As I said earlier, Kris Russell often maintains a very large gap in an attempt to block shots.

          The one thing that you have not done is over commit to make a shot block. Also if you do shot block you have also had your man covered also.

          In theory, yes. However, one would assume that if you have your man “covered” you should be able to make a better play than blocking a shot (for example, taking away possession).

          Of course your getting a shot against but never a goal against when you have made a shot block.

          Again, correct, in theory. How many goals have we seen scored against
          The Flames where a shot is partially blocked, takes a strange deflection and ends up beating an otherwise well-positioned goalie? Too many times to count. You’re right. If you block a shot and it hits you right in the shin-pad or chest and lays flat in front of you with enough time to recover, then you’re in good shape. That’s no reality though. As the stats in the article indicate, blocking a shot does not drastically change who is in possession of the puck.

          It is just important to keep the puck out of your net as it is to score goals.

          You’re correct. That’s the point of this article. Again, I’ve never said blocking shots is inherently negative. I’m simply arguing a defensive scheme principally based on blocking shots is flawed, because it belies other, more effective means of defending.

          Blocking shots win you hockey games that is a fact.

          Is it? Who had more shot blocks between the Flames and Ducks in the playoffs last year? Who had more shot blocks between the Hawks and Lightening? Who had more shot blocks between Canada and the US in the olympic semi-final in 2014?

          Well timed blocks? Sure. On an individual level, yes, there are players that block shots, and they do it well, and it contributes to winning. However, on the macro level, more blocks in a game (series, season, whatever) is not corollary to winning. In fact, over the long term it’s quite the opposite. It usually proves that a team spends more time defending than it does attacking, and that is a bad thing.

  • ChinookArchYYC

    Blocking a shot should be the second last line of defence; the last being the goalie making the save. If our defenders actually hit and pinned people coming down the wing there would be no need to block as many shots. Instead they almost always let the forward pass them; Spanish Hockey olay. With the ability of Gio, Brodie, Hamilton, Russell and to a lesser extent Wides to skate if their partner hit and pinned the winger (you don’t have to crush them) and separate the pucker carrier from the puck their partner would be able to retrieve the puck and clear the zone easier. We need a young Robyn Regher style defender to play with each of the big 3.

  • cberg

    This is a great article to point out a few things, some which you might not agree with, but hey, them’s stats….

    First some comments on the article. First there appears to be a very slight increase in additional shots after a block vs a shot. OK, its a negative towards blocks but its pretty negligible. Secondly, there seems to be a significant increase in play stoppage after a shot versus a block. The stated assumption is that stoppage is a positive outcome, but actually its the opposite. Since the potential of additional shots after a block is negligible (pt. 1) we have to assume the puck gets out and eventually we get possession, or there is a stoppage. Since getting the puck out and possession is a positive outcome the higher chance of that happening the better. Further, if there is a stoppage it goes to a face-of If the face-off is after a goal (likely ~10% of the time) that’s definitely a huge negative versus a block. If there is no goal but the puck is frozen, we’d have to win >50% of Face-offs before that was a positive outcome, and we all know that isn’t happening too often. The factor of getting fresh bodies on the ice is also a positive, but since it happens for both teams its more a draw.

    Now, let’s examine the blocked shot stats. The writer compares the Calgary Flames versus the NJDevils. Fine.

    Flames: 898 Corsi Events, 284 shots blocked(32%), 614 shots “towards the net”, which includes both shots on net and shots missing the net. For discussion purposes let’s assume 25% of Corsi Events miss the net (reasonable, check the numbers). Therefore, 224 shots miss the net (25% Corsi Events), and 390 Shots on Net. Assuming for discussion purposes 10% SON are goals = 39 goals against.

    NJDevils: 777 CE, 204 SB(26%), 573 Shots towards net. At 25% Corsi as Missed the net provides 194 MTN, totalling 379 SONet. At 10% Goals = 38 goals against.

    Now, let’s accept the writer’s premise that blocked shots are bad. Let’s assume Calgary blocks shots at the NJD’s slightly lower rate of 26%. The numbers, please: 898 CE, 233 SB(@26%), 224 MTN yielding 441 SONet. At 10% goals = 44 goals against.

    Therefore, injury issues aside (it is a factor, but for stats clarity), NOT BLOCKING shots (i.e. NJ Devil’s LOW block rate) means we give up an additional 5 goals versus high blockage. 5 extra goals against would be what? 5 additional losses? No, probably not. 0 additional losses? Not likely either. Let’s split the difference and go with 2-3 additional losses (in line with some numbers I’ve seen a while back), 4-6 less pts which is VERY SIGNIFICANT.

    So, you see, BLOCKS MATTER! The fallacy in the writer’s arguments is that he ignored the fact that 100% of the shots you block do not score a goal, while ~10% of the ones that hit the net do. When you look at the WHOLE picture, the story is completely different.

    • piscera.infada

      Have you taken the time to review game tape to see how many goals were caused by blocking shots though? This would include anything like a player being out of position, a “bad” deflection that wouldn’t have otherwise occurred, or any of a multitude of other possible scenarios.

      Your argument is flawed because it assumes that blocked shots (in a macro sense) have no negative impact at all (outside of injury).

      • cberg

        First off, I agree that those things occasionally happen, though personally I don’t think it’s many. Outside of tips, and those aren’t actually blocked shots though I agree they are probably related with trying to block shots.

        My argument doesn’t assume only injuries are bad outcomes, I’m just looking at the stats and making the point that all true (as defined by stats keepers) blocked shots never score a goal, and unblocked shots fairly regularly do. You can’t make a true statistical argument until you consider and incorporate this fact into your analysis.

        Now let’s get back to the occasional accidental deflection. I agree these occur. I also think they may be a lot more prevalent than I am believing, I can’t really say. Ultimately I’m not sure anyone can. Who tracks small deflections? If you know of someone let me know. But this is really a totally different discussion than this article, which is bogus.

  • cberg

    While we’re talking about meaningful stats, here’s one I saw in the last two games on the TV broadcast.

    First stat: Average number of times a team created a pass into the slot where a Corsi Event (shot toward the net) was subsequently taken. Calgary was #1 in the NHL in this stat, providing a league-best number of great scoring chances in great scoring areas.

    Second stat: Number of these shots that actually became Shots on Net. Calgary was I think 27th in the league in this stat.

    What seemed very clear and the point that was being made on the broadcast was Calgary’s inability to hit the net on their shots, having a lot of shots missing the net. Actually it was mentioned last game because they were noting that Frolik really made sure to hit the net on his goal.

  • ChinookArchYYC

    Good stuff Clib542.

    Maybe I’m the only one to be irked be Hartley’s “shrugged it off” attitude, when asked about potential injuries. No wonder the Flames players hate him (according to Elliot Freidman).

      • ChinookArchYYC

        Thanks for challenging me. I’ve removed the comment referring the rumour that I heard regarding the Flames medical staff.I personally believe the source, but I cannot substantiate. I really don’t like when other fans post rumours and so I won’t either. As for the Flames aledgedly hating Hartley, that was well documented, and I’ll look for the link later.