Does Blocking shots at a higher rate help win games?

[Cunneen]

Most people in the advanced hockey metrics community are aware that Blocked shots correlate slightly negatively to winning (in other words, teams with a lot of blocked shots will usually have less wins and a worse goal differential than teams with smaller blocked shot totals). This is because a blocked shot for team A actually shows us that Team A didn't have the puck.

However, I thought it would be interesting to calculate the ratio of blocked shots per total shot attempts. I wanted to do this to determine which teams blocked more shots per shot attempt, which teams got more of their shots blocked per shot attempt, and whether that correlated at all to winning and or scoring goals.

Calculating the percentage of shots a team blocks (compared to their total shot attempts total) or the percentage shots a team took that got blocked is very easy. NOTE: all numbers are courtesy of stats.hockeyanalysis.com and are at even strength (5v5) and not including any situations with the goaltender pulled.

Blocked Shots percentage For = Blocked shots by team/ Corsi against *100

Blocked Shots percentage against= Blocked shots by opposing teams / Corsi For*100

(Corsi is equal to shots on goal + miss shots on goal +blocked shots).

First, I will do Blocked Shots percentage against for the past three seasons. (Look at first attachment for the graph with the results). Remember, this stat shows the rate at which a team's shots get blocked by the opposing team.

On the X axis are the blocked shot percentages against. On the Y axis is the Goals For%.

The R^2 value for this data was .00085. In other words, no correlation at all.

Second, I will do Blocked Shots Percentage For (past three seasons). (second attachment)

Remember, this stat shows the rate at which a team blocks their opponents shots.

On the X axis are the blocked shot percentages against. On the Y axis is the Goals For%.

The R^2 value for this data was .01695, Again, too low to show any correlation between shot blocking rates and goal differential percentage



Conclusions:

From the data it seems to me that shot blocking rates have little effect on goal differential. While past research has determined that the # of shot blocks is usually lower for a better team, the rate at which an individual team either blocks shots or gets their shots blocked compared to total shot attempts against/for seems to be very close to irrelevant.


Any Thoughts??

Click to read more...

 

[Bear of Bad News]

I'll comment more in a bit (when I'm not on a small screen), but this is very interesting.

 

[pdd]

It's because blocked shot data isn't comprehensive enough; an intentionally blocked shot where the winger goes out and drops to his knee and the puck rebounds off of him and out of the zone, that's a blocked shot.

A shot into traffic that hits the leg of an unsuspecting opposing player and bounces back towards the blueline? Also a blocked shot.

A pass through the crease to a player set up for a tap-in goal on the far post that deflects off of the defenseman's skate and away from the net? It's a blocked shot!

A slapshot off a forward's stick and into his jaw? BLOCKED SHOT!

Obviously not all of these will always be scored this way (human factor in RTSS) but they can legitimately be. Not unlike the WP vs. E2 in baseball. Did the catcher have a realistic chance at actually catching the ball? Basically, it's "If yes, E2. If no, WP." And that's completely a judgement call, in many cases made incorrectly IMHO.

 

[Cunneen]

Update:

I dove further into this data.

I realized that the Blocked Shots percentage for only tells the defensive side of the story, while Blocked Shots percentage against tells the offensive side. So I decided to combine to two numbers into Total Blocked Shots percentage:

TBSP= Blocked Shot percentage For - Blocked Shot Percentage against

A positive TBSP means that a team blocks a higher percentage of shots than their opponents block of their shots. In other words, a positive TBSP is good, while a negative TBSP is bad. Not surprisingly, the Rangers were the team with the best TBSP, since they block the highest percentage of their opponents shots.

I'll update later on whether TBSP correlates or not with Goals For %, but TBSP is definitely a better measure of whether blocked shots on both ends of the ice are hurting or helping.

 

[Cunneen]

I've looked at the difference between Blocked shot percentage for and Blocked shot percentage against (which formulates a new stat we can call Total Blocked Shot percentage, or TBSP). I graphed this new stat again comparing to to the Goals For%. You can see the graph in the attachment.

Few Things to note from the data:

TBSP seems to be a repeatable skill. Top teams in this stat (rangers, tampa Bay, islanders) are seen multiple times near the top of the ranking. It seams that shot blocking and/or not getting one's own shot blocked is a repeatable skill, though my guess it is influenced heavily by the style of one's coach.

R^2 value for TBSP in relation to GF% is .0125. Similar to previous data, no correlation at all.

I want to note that I have not adjusted for rink biases (don't have the data and/or time).

My next post will be to adjust for the save percentage of each team (this is affecting the GF% and thus needed to be adjusted for to get a better sense of whether TBSP can correlate at all to GF%.)

 

[Cunneen]

Update!!!!

UPDATE: I am running new data that graphs Blocked shot percentage compared to metrics such as Corsi against, goals per corsi event against, Fenwick against, and other shot metrics, rather than GF%. This should measure more accurately the value of the blocked shots.

 

[Cunneen]

Sorry I haven't updated this recently (AP exam week this week so I'm kinda swamped). I have run a few #s but haven't found anything significant. I'd love to hear from anyone with some ideas on how to show the importance(or lack thereof) of Shot Blocking rates for and against.

Hopefully this weekend I can dive deeper into the numbers and find some answers

 

[Rorschach]

Kings believe something different. They try not to have shots blocked as a primary way of stopping shots. They will attempt blocks if the primary way has failed of course, the opposing player somehow can shoot unhindered. The primary method will be to check sticks and poke the puck. Active sticks are better because when you go to block a shot, you might miss or deflect the puck or have get injured from the impact of the puck or stick-in-motion. All of these things happen all of the time...plus on top of that, it means the opposing player gets to shoot...and good things happen if you shoot enough on net. So to the Kings, shot blocking is an inferior way of defending the puck, compared to stick checking, stick poking, pushing the puck and play away from the middle of the offensive zone or simply body checking the opposing player so that he loses possession of the puck in the offensive zone. The latter in theory is a good play because you're supposed to outnumber the offense down low...and it becomes a very solid play if you have immediate puck support from a team mate.

It's why the Kings last year were so tough to play. They were rough, got their scoring chances but also killed 90% of your 5x5 plays just by poking the puck and keeping it outside, then using little high percentage tap passes by the stationary player on the outside, just under the point, to a player with a quarter-head of steam skating out of the zone, starting an offensive rush. It also helps that we have a PMD on each pairing and each of our veteran d-men has a good, normal outlet passing ability as well.

It's extremely annoying to the opposing offense and highly effective. Just ask Blues' opponents. You work so hard to get the puck in the zone, the Kings just tap, tap, tap and it's back out so easy. And if there's a semi-lucky bounce and you get to shoot, you have to beat Jonathan Quick.

 

[SaskRinkRat]

This is really good stuff, Cunneen. I have run a similar analysis before and found similar conclusions, though I focused mostly on goals scored and points generated, so you've taken it a step further.

To me, the really interesting things is why shot blocking is virtually irrelevant, even when expressed as a rate of shot attempts. It seems so intuitive that a team that blocks more shots per shot attempt against should win more games, but it's simply not the case. I'm working on trying to figure out how to use available data to test a few hypotheses.

Good work.

 

[Cunneen]

This is really good stuff, Cunneen. I have run a similar analysis before and found similar conclusions, though I focused mostly on goals scored and points generated, so you've taken it a step further.

To me, the really interesting things is why shot blocking is virtually irrelevant, even when expressed as a rate of shot attempts. It seems so intuitive that a team that blocks more shots per shot attempt against should win more games, but it's simply not the case. I'm working on trying to figure out how to use available data to test a few hypotheses.

Good work.

Thanks. I'd love to see your research and what you have found. If you get the chance email it to me at [email protected] or just post it on this thread.

As I said in my previous post, I have some more data that I will look at probably today and tomorrow and will let everyone know the results.

So far it does seam that shot blocking is seemingly irrelevant. But surprising results require conclusive evidence, so I'm not yet done with the research.

 

[SaskRinkRat]

I've attached a .png with a couple of graphs I generated comparing shot blocking rates to points and goal production. Seems like essentially the same analysis you produced, though yours went further.

 

[Sixbladeknife]

Very nice work! It is indeed very interesting that there's no correlation. Maybe blocking a lot of shots means that the ones getting through are a lot more dangerous? I know the shot quality effect seems to be quite small in the studies I've seen, but off the top of my head I really can't come up with a better explanation.

If you have the time and effort, you could try fooling around with team SV% and see if a negative correlation emerges.

 

[Cunneen]

Very nice work! It is indeed very interesting that there's no correlation. Maybe blocking a lot of shots means that the ones getting through are a lot more dangerous? I know the shot quality effect seems to be quite small in the studies I've seen, but off the top of my head I really can't come up with a better explanation.

If you have the time and effort, you could try fooling around with team SV% and see if a negative correlation emerges.

I have similar suspicions. I'll let you know what I find.

 

[Cunneen]

Been awhile since I last posted on this thread.

So here is the basis of what I have found throughout this research:

1) First point is very simple (and I basically already knew before the research this but it's worth mentioning). When looking at a team's ability to block shots, we should focus on their blocked shot rate (blocks shots / Corsi events) rather than total # of blocked shots, since total # of blocked shots is more a reflection of a bad possession team than a good shot blocking team

2) Rate at which a team blocks shots is independent of the # of shot attempts that team lets up. This basically means that a team can be really good at blocking shots without having a really high Corsi against number. There was no correlation between Corsi against and Blocked shot rate.

3) Blocked shot rate seems to be a skill that can be repeated to a point. Now I did not use nearly enough years of data to be sure, but from my data there was a decent correlation between Blocked shot rate from year to year for teams.

4) One thing I was unhappy about was my lack of ability to full determine how valuable it was to have a good shot blocking rate. At first I tried comparing it to Goal differential, but what I soon realized is that there are other factors (like Corsi For % and a team's goalie) that has a much greater impact on a team's goal differential than blocked shot rate. This probably comes from my own inexperiance but I was unable to figure out a way to fully isolate and determine the value of a higher blocked shot rate. (anyone more knowledgeable in this area who has an idea of what to do please let me know). I think that common sense tells us that it is always better to have a blocked shot compared to a shot on goal. Thus, a higher blocked shot rate would be favorable. However, I have no data to back that conclusion up.


I'd love to hear your guy's thoughts. If anyone has any idea on how to isolate the importance of blocked shot rate I'd love to hear it.

 

[thom]

I read a stat that said LA Kings won cup despite blocking the least amount of shots.Can someone back that point?

 

[Hammer Time]

Been awhile since I last posted on this thread.

So here is the basis of what I have found throughout this research:

1) First point is very simple (and I basically already knew before the research this but it's worth mentioning). When looking at a team's ability to block shots, we should focus on their blocked shot rate (blocks shots / Corsi events) rather than total # of blocked shots, since total # of blocked shots is more a reflection of a bad possession team than a good shot blocking team

2) Rate at which a team blocks shots is independent of the # of shot attempts that team lets up. This basically means that a team can be really good at blocking shots without having a really high Corsi against number. There was no correlation between Corsi against and Blocked shot rate.

3) Blocked shot rate seems to be a skill that can be repeated to a point. Now I did not use nearly enough years of data to be sure, but from my data there was a decent correlation between Blocked shot rate from year to year for teams.

4) One thing I was unhappy about was my lack of ability to full determine how valuable it was to have a good shot blocking rate. At first I tried comparing it to Goal differential, but what I soon realized is that there are other factors (like Corsi For % and a team's goalie) that has a much greater impact on a team's goal differential than blocked shot rate. This probably comes from my own inexperiance but I was unable to figure out a way to fully isolate and determine the value of a higher blocked shot rate. (anyone more knowledgeable in this area who has an idea of what to do please let me know). I think that common sense tells us that it is always better to have a blocked shot compared to a shot on goal. Thus, a higher blocked shot rate would be favorable. However, I have no data to back that conclusion up.


I'd love to hear your guy's thoughts. If anyone has any idea on how to isolate the importance of blocked shot rate I'd love to hear it.

Do you know if there is any correlation between shots allowed and shot blocking rates? Intuitively, teams which block a higher percentage of shots should allow less shots on goal, and thus have a higher goal differential and chance of winning.

 

[Bure All Day]

the stats are not that important to me, because shot-blocking is such a small part of an entire team's make-up that the effect it's going to have on the overall success of a team is going to be pretty insignificant.

The success of a team is determined by soo many more factors than blocked shots that it's difficult to use it alone to see if it helps a team or not

 

[Cunneen]

the stats are not that important to me, because shot-blocking is such a small part of an entire team's make-up that the effect it's going to have on the overall success of a team is going to be pretty insignificant.

The success of a team is determined by soo many more factors than blocked shots that it's difficult to use it alone to see if it helps a team or not

I agree, but its interesting nonetheless.

 

[Cunneen]

I read a stat that said LA Kings won cup despite blocking the least amount of shots.Can someone back that point?

The Kings blocked 715 shots last year at even strength during the regular season, the lowest in the NHL. There are two reasons: 1) the Kings had the second lowest Blocked shot percentage at even strength at 22.92% . 2) The kings were such a good possession team last year that they let the third least amount of Corsi against.

So yes, at even strength in the regular season they were awful at shot blocking.

 

[Cunneen]

Do you know if there is any correlation between shots allowed and shot blocking rates? Intuitively, teams which block a higher percentage of shots should allow less shots on goal, and thus have a higher goal differential and chance of winning.

It would be hard to figure out because there are other factors that have a greater effect on shots allowed. A really bad team could give up a ton of shots but be a really good shot blocking team.

Of course if you have two teams that give up the same amount of shot attempts (shots + missed shots + blocked shots) and one team blocks at a much higher rate then that team will give up less shots on goal than the other team. So blocking shots at a higher rate can be a significant factor, but i'm just not always sure how to isolate the importance of shot blocking rates.

 

[Bure All Day]

I agree, but its interesting nonetheless.

What's interesting is that blocking shots doesn't seem to have much, if any effect on goals against.

You'd think teams with the most blocked shots would have at least like 10% less goals against or something, but I guess what this really shows is that by blocking more shots, a team is also giving up more shots, which in turn results in more goals against. Plus blocking shots often just returns the puck to the player(s) who had control of it before anyways, so they're just going to keep shooting until they get one on.

Obviously there are going to be instances where a blocked shot actually does save a goal, but apparently not enough to make a big impact

 

[Green Blob*]

Looks at Rangers...


Nope.

 

[Cunneen]

What's interesting is that blocking shots doesn't seem to have much, if any effect on goals against.

You'd think teams with the most blocked shots would have at least like 10% less goals against or something, but I guess what this really shows is that by blocking more shots, a team is also giving up more shots, which in turn results in more goals against. Plus blocking shots often just returns the puck to the player(s) who had control of it before anyways, so they're just going to keep shooting until they get one on.

Obviously there are going to be instances where a blocked shot actually does save a goal, but apparently not enough to make a big impact

No, I wouldn't think that a team with more block shots would have less goals. Any logical person would know that more blocked shots equals more shots against means other team has the puck.

The point I'm making is that we should look only at blocked shot rate (which is independent of possession statistics).

 

[Cunneen]

Looks at Rangers...


Nope.

Not sure what your trying to say here

 

[ItsthatSimple]

I believe the more you have blocked shots the better of a chance the other team has to score since they know to be more patient with the puck before they shoot.