Terminology
- Thread starter CroJack
- Start date
Don't know, CJ. I've never heard that term before but then I've never heard of any term used to describe that particular space. If something comes to me I'll post it here.
CroJack
Key Player
What about goalmouth?
Actually the term was used some 65 years ago by our coach Mr Walsh, when I played for the schoolboys, He used to tell our keeper in the event of a penalty, stand about a yard one side or the other of your centre line "Show him more goal opening, then when he took the kick dive to that side.".
I Know it doesn't answer you question CJ, but it did bring that to mind all that time back.
I Know it doesn't answer you question CJ, but it did bring that to mind all that time back.
Behindthegoal
Key Player
I see where you’re coming from CJ.
You will have to coin a phrase. How about “open” or “unguarded” area.
Obvoiusly with our goalie it’s irrelevant.
You will have to coin a phrase. How about “open” or “unguarded” area.
Obvoiusly with our goalie it’s irrelevant.
You mean that ALL the goal is open whenever he's between the sticks?
CroJack
Key Player
I thought about unguarded and undefended goal area. But in the case above it's guarded and defended by the goalkeeper.
Also, when we use term "area" then it's normally an area on the pitch. Goal area is area just in front of goal.
"Empty net" can't be used either because then there is no goalkeeper between the sticks.
CroJack
Key Player
Thanks mate. Of course it answers my question.
I am glad such term exists. Especially when a football coach uses it. It doesn't matter the last time it was used was 65 years ago.
Spoken and written English was much richer 60-70 years ago.
Yankee_Jack
Key Player
If Woody is playing then "goal-opening" is 100%.
Perhaps you could think of it as a target area. Goal Target = Goal Mouth (8yds x 8 ft) - Keeper's Frame ((Height + Reach) x (Width + Reach)).
The target area being that part of goal mouth not covered by the oblique projection of the keeper's frame.
How do you determine keeper's width and reach is going to be difficult. Perhaps you could standardize the Keeper's Frame based on height, after sampling a dozen (?) people of varying heights and builds and creating a lookup table. Thereafter, if you know the keeper's height, applying that value to the Frame Model would give you the Keeper's Frame +/- std_dev.
In your graphic you are framing the keeper with arms down and to the side, so the frame is just a standard body bounding rectangle.
To complicate things, the frame will be time / reaction speed variant. A flapper like Woody would flap his arms up and down and be generally slow to react. Some keepers would kick away/block a low shot with their foot; others would attempt to dive (i.e drop low) and use their hands and body. I argue the former would be more effective if reaction time is limited, but you don't often see that and I've never noticed Woody employ that practice.
It's strange that I'm referring to Woody, but to me he exemplifies everything lacking in a good keeper, but is still considered competent at his position, and therefore suggests a baseline,
I have recently watched videos of Alex Stepney and Peter Bonetti and at the time they were considered top keepers (alongside Bob Wilson, Jennings, Shilton et al and before them Banks and Springet), but most of their peers had similar skills and abilities to actually catch and retain the ball on a save instead of just parrying it away ... do players shoot the ball any harder today ... I don't think so (even defenders back then - e.g. Norman Hunter - could drill a ball on target from distance). There are competencies in keepers of yore that far exceed those of the modern keeper - IMO.
Perhaps you could think of it as a target area. Goal Target = Goal Mouth (8yds x 8 ft) - Keeper's Frame ((Height + Reach) x (Width + Reach)).
The target area being that part of goal mouth not covered by the oblique projection of the keeper's frame.
How do you determine keeper's width and reach is going to be difficult. Perhaps you could standardize the Keeper's Frame based on height, after sampling a dozen (?) people of varying heights and builds and creating a lookup table. Thereafter, if you know the keeper's height, applying that value to the Frame Model would give you the Keeper's Frame +/- std_dev.
In your graphic you are framing the keeper with arms down and to the side, so the frame is just a standard body bounding rectangle.
To complicate things, the frame will be time / reaction speed variant. A flapper like Woody would flap his arms up and down and be generally slow to react. Some keepers would kick away/block a low shot with their foot; others would attempt to dive (i.e drop low) and use their hands and body. I argue the former would be more effective if reaction time is limited, but you don't often see that and I've never noticed Woody employ that practice.
It's strange that I'm referring to Woody, but to me he exemplifies everything lacking in a good keeper, but is still considered competent at his position, and therefore suggests a baseline,
I have recently watched videos of Alex Stepney and Peter Bonetti and at the time they were considered top keepers (alongside Bob Wilson, Jennings, Shilton et al and before them Banks and Springet), but most of their peers had similar skills and abilities to actually catch and retain the ball on a save instead of just parrying it away ... do players shoot the ball any harder today ... I don't think so (even defenders back then - e.g. Norman Hunter - could drill a ball on target from distance). There are competencies in keepers of yore that far exceed those of the modern keeper - IMO.
My take on this, Yankee, is that in those days footballs were heavier, held water and were easier to deal with. Today, balls tend to be lighter, more waterproof therefore tend to swerve and dip much more than did the old ones making it more difficult for keepers to take and catch. Also, today's footy boots are designed to develop this swerve and dip in flight which the old-fashioned clog type boots never could. Mind you, the likes of Ivor and the other top players still managed to get some 'work' on the ball when they struck it.
CroJack
Key Player
Target area is interesting.
It's actually not.
I don't do standardisation because every chance is unique and every keeper has a different height and body position.
Exactly.
Calculating time of reaction and speed of ball is not necessary. Goal opening (target area) is always same. And if the shot is powerful enough the goalkeeper can't react. A chance doesn't have a lower value just because a player can't shoot properly.
Yankee_Jack
Key Player
The Mitre balls used in the late 60's (at least) and beyond were vinyl clad and didn't absorb moisture like the old dubbed leather with bladder and lace balls.
During the 1970 World Cup when the Brazilians showed up and were bending the ball all over the place from shots and free-kicks, Malcom Allison appeared on Blue Peter and demonstrated how they made the ball curve. I think he also did the same demo on whatever sport channel he appeared on - can't remember whether it was with Jimmy Hill on BBC or whatever ITV channel had the rights. Of course I tried that and it fucked me up for years kicking the ball straight.
Watch some of the old Stepney videos (search by George Best to find them) and you will see him do some excellent work. Search by Ian St John and you'll get to see Tom Lawrence at 'Pool. Search Colin Bell and you'll see the Corrigan at City. Excellent goal keeping ... when keepers were not a protected species and were expected to put their body on the line.
Several years back I was at Villa Park and saw the Swans get their first away win under Rogers in the Prem. At half-time, in one of the posh bars under the main stand, was Jimmy Rimmer - a lonely soul - with every finger in both hands pointing in weird directions and at the joints at funny angles as if every single one had been broken multiple times. There's no way he could hold a cup of tea normally. And also, lurking in the shadows not trying to attract attention was David Moyes sipping a cup of tea - we were due to play them next.
I remember being at the Vetch for a Wales v N.Ireland game I was at the corner where the East Stand met the Small bank. I was right in line with the corner flag. Best came over to take a corner ,the ball went straight until it got into the box and then it turned left. I put this down to wind .But he went on to take a couple more corners and the ball followed the same pattern .
Yankee_Jack
Key Player
It was 1970. I was at that game in the Enclosure. Millington was in goal and made a spectacular save from Best taking a free kick over the wall at the Double Decker end. Ronnie Rees scored our goal; same end.
Yankee_Jack
Key Player
It’s bizarre. I can remember all of those match details from 51 years ago like I just walked out of the ground at the end of match. But, I’m damned if I can remember why I walked into this room just now. 
I once sold car to an Egyptian brain surgeon working in our Withybush Hospital back in the 70's and we became quite friendly, he used to occasionally come to dinner, Obviously there were times when the conversations turned to the brain. His explanation to me, a layman, was think of your brain like the ribbon in a typewriter, first used very clear, but after a lot of used some words become indistinguishable,, That's always stuck in my head, it's a fair description, and like yours Yankee is barely readable now.It’s bizarre. I can remember all of those match details from 51 years ago like I just walked out of the ground at the end of match. But, I’m damned if I can remember why I walked into this room just now.
Yankee_Jack
Key Player
@CroJack ... back to the thread ... my definition of Goal Target above is only valid in the trivial case of the Forward standing any distance out but dead center of goal, and the keeper standing on the goal line. In this case, the Woody case, there is no perspective and no projection. However, as the forward moves around the goal, and the keeper advances off his line the Goal Target becomes
GoalTarget = Area(P(Goal Mouth Bounding Box)) - Keeper’s Frame
where:
There are a number of variables that factor into the Goal Target ... or the unblocked area that the forward sees. Adding further complexity there is a distance between the forward’s eyes and his feet. What the forward sees visually is not what his feet or ball “see”; there’s a 6’ +/- difference in the point of perspective. The shape of the Goal Target by eye will differ from the shape of Goal Target by foot/ball in the vertical direction; hence the value of Goal Target will also differ.
GoalTarget = Area(P(Goal Mouth Bounding Box)) - Keeper’s Frame
where:
- P() is the perspective projection transformation of the goal mouth onto a plane perpendicular to the line joining the forward and the keeper.
- Area() is the function that calculates the area of the projected goal mouth.
There are a number of variables that factor into the Goal Target ... or the unblocked area that the forward sees. Adding further complexity there is a distance between the forward’s eyes and his feet. What the forward sees visually is not what his feet or ball “see”; there’s a 6’ +/- difference in the point of perspective. The shape of the Goal Target by eye will differ from the shape of Goal Target by foot/ball in the vertical direction; hence the value of Goal Target will also differ.
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Yankee_Jack
Key Player
I should add that the plane into which the goal mouth is projected passes through the keeper. The plane is normal horizontally to the keeper/forward line, but is going to have a different inclination from the vertical depending on whether the point of perspective is the forward’s eyes or feet.
A keeper will probably position relative to the Forward’s center of mass and not the kicking foot, which would be a different alignment. In a game of fractions that little shim might make all the difference.
A keeper will probably position relative to the Forward’s center of mass and not the kicking foot, which would be a different alignment. In a game of fractions that little shim might make all the difference.
CroJack
Key Player
Exactly. That's how I calculate expected goals.
First, the goal opening (the undefended target area) has to be calculated, then the distance and angle. But that's not a problem. It's a basic geometry we are talking about.
When I did calculations for Swansea and Brentford expected goals for this season the main problem was the lack of good camera angles. So I had to put every chance with players positions in 3D application Blender. Only then I was able to see chances from all perspectives and calculate correctly xG.
As far as I know, in Britain only the new White Heart Lane has high speed cameras everywhere inside the stadium. Also above the pitch.
It doesn't matter what the forward sees. What matters is what the ball 'sees'.
Yankee_Jack
Key Player
What the player does with his feet is driven by what he sees through his eyes ... perhaps that's why they fail to score when they should ... they don't map properly. What the ball "sees" is what the ball encounters.