The penalty was invented on February 14, 1891. It was the last minute of an FA Cup quarter-final between Notts County and Stoke City when a defender for County stopped a shot on the line with his hand. Stoke were awarded a free kick just centimetres from the goal-line and the goalkeeper, as was perfectly legal at the time, stood right in front of the ball. The Stoke player, unable to do anything other than kick it straight at him, saw his shot blocked in farcical circumstances.
At a subsequent meeting of the International Football Association board in Glasgow on June 2, 1891, a motion for a new penalty kick law was tabled by the Irish FA. The board approved and, just like that, decades of anguish and joy was born. Sort of. The original rule stated players could take a penalty “from any point twelve yards from the goal-line” and the keeper could advance at least six yards to save it. But, over time, they have been tweaked and finessed into what we know and love/hate today.
Penalty shootouts were only introduced to the World Cup in 1978 and 26 had taken place before the 2018 tournament started. The likelihood of any penalty being scored is around 70 per cent, a stat perfectly reflected by the World Cup penalty shootout success rate, which counts 170 successes from 240 penalties taken from shootouts before the tournament in Russia. But why twelve yards? Simple: that’s what the FA decided in 1891. And it’s likely never been changed because scoring seven out of every ten penalties gives a good mix of risk, reward and drama.
Move the ball any closer or further away and the odds start to tip too far one way or the other. As John Wesson points out in The Science of Soccer, taking into account air drag, a perfectly directed ‘penalty’ hit at 80mph into the top corner of the goal could, in theory, defeat a goalkeeper from 35 yards. Move ten yards or closer to the goal and the likelihood of scoring rises steadily. At three yards, it is almost 100 per cent.
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Seemingly by fluke, 12 yards is pretty much the sweet spot: enough penalties go in to reward skill and good placement and enough penalties are saved to reward good guesswork and agility by goalkeepers. Of those 240 World Cup final shootout penalties attempted, only 49 have been saved – 24 made by keepers diving to the left and 25 made diving to the right.
As Harry Kane showed in his two spot kicks against Panama, relying on physics to score the perfect penalty is all about two things: speed and direction. At 80mph, a goalkeeper has about one-third of a second to make a save. As this is similar to their reaction time, the only chance of it being saved is to guess right. And that’s where placement comes in. Research carried out by the University of Bath in 2012 found a “diving envelope” for any given keeper if they push off in any direction with maximum force. The probability of scoring inside the diving envelope is 50 per cent. The probability of scoring outside the diving envelope is 80 per cent.
In terms of goal area, that gives the keeper a technical advantage: they can reach 70 per cent of the goal area, leaving a penalty taker with 30 per cent of the goal to aim at to dramatically improve their odds of scoring. And if they hit it, they invariably score. Data from Opta (via the BBC) shows that no goalkeeper in World Cup history has ever saved any of the 15 World Cup shootout penalties struck high and centrally (think about it: when did a goalkeeper ever jump straight upwards?) while striking the ball low and in the middle drops the success rate down to 58 per cent. Of penalties taken in World Cup shootouts, 90 per cent hit high and either side of the centre (as with Kane versus Panama) were converted.
For Kane, as with other top penalty takers, having a top conversion rate is all about preparation. In league and international football, Kane has taken 27 penalties and scored 22, a success rate of 81 per cent. “I try to practice all different types of situations and make sure I’m ready for anything that comes,” Kane said in an interview this week. When the time comes, Kane already has a plan in place for how he is going to score a penalty. That clarity of mind, combined with great technique, increases his chances of scoring. “I’m ready for everything, whether it is a penalty, a set-piece,” he said.
So what does this all mean? If you want physics on your side, aim high and hit the ball hard. In this regard, one fairly recent rule change that was designed to help goalkeepers may have had the opposite effect. Until 1997, goalkeepers had to remain stationary in the centre of the goal until a ball was struck. Since the rule change, they’ve been allowed to bounce along their line, dramatically changing the range of their diving envelope. This means they can potentially reach far more of one side of the goal, but leave the other side wide open. As we’ve seen at this World Cup, clever penalty takers now use this to their advantage by subtly changing the speed of their run up to shift the goalkeepers weight.
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Research conducted by Exeter University, in 2009, tracked the eye movement of footballers when taking a penalty. Sports scientists gathered 14 university-level football players and fitted them with special glasses to track their eye movements. They were asked to attempt two types of penalty. First, the researchers asked them to try their best to score. In the second round, they were told their efforts would be recorded and shared with other players and that the best penalty taker would receive a £50 prize. This was designed to increase the pressure of taking the penalty – although doesn't mimic the pressures of a real-world spot kick. The results showed that when anxious, footballers looked at the goalkeeper significantly earlier and for longer, making it more likely that a player would focus on the keeper and shoot more centrally. Penalty takers who focussed too much on the goalkeeper saw their attempts saved 40 per cent of time the, compared to less anxious players who were able to ignore the goalkeeper, resulting in a lower save rate of 20 per cent.
Physics is all well and good, but as the eye-tracking experiment shows footballers are not robots. And under the most extreme pressure it turns out the brain plays even crueler tricks on you.
According to researchers from Bangor University, players consistently miss vital penalties by inadvertently making the exact error they are trying to avoid. The so-called “ironic error” effect is the result of players subconsciously assessing all the likely outcomes and then becoming overwhelmed. In a high-pressure situation like a World Cup penalty shootout, knowing that you could hit the post overrides the more statistically likely outcome: they you should score. Simply put: under immense pressure to score a penalty, the mind is drawn ever close to focussing on how you could miss. The result? You miss. And football is no longer coming home.