With the FIFA World Cup 2022 semi-finals in Qatar just around the corner, many are wondering what makes the perfect penalty.
University of Queensland (UQ) researchers have developed a model to determine the best outcome for the spot-kick taker. Their analysis is published in the Journal of Biomechanics. For those who cant wait, their findings are at the foot of this article…
Their research may be welcome news for football (yes, I will insist on saying “football”, not “soccer”) strikers as this edition of the World Cup has seen more penalties saved by keepers or missed than ever before. So far, in this World Cup, there have been 51 penalties (including penalty shootouts), with only 32 of those scored – or a conversion rate of just under 63 percent.
Former England football team captain Rio Ferdinand told BBC Sport that he thinks penalty takers are getting too casual. “I think that’s the way penalty takers are going at the moment. You have to score otherwise you look like an idiot,” he said.
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Mark Schwarzer, former Australian World Cup goalkeeper, said on Optus Sport’s GegenPod podcast: “I think goalkeepers are simply getting better. There’s a lot more research put into it, a lot of time and effort spent on goalkeepers to find those find margins, those one-percenters. It’s very much what goalkeepers are doing.”
Schwarzer believes that the additional research done by goalkeepers is placing more of the onus on the striker to score.
“The analysing that goes on is on another level. The pressure is always on the kicker. The goalkeeper does everything right, does all the research and gets into the head of the penalty taker without going too early then there is a chance (he will save it). But still, it’s still heavily in favour of the kicker but goalkeepers are getting better and better all the time.”
Shootouts were only brought into FIFA World Cups in 1978 with the first shootout at the tournament in 1982. They replaced the previous method of settling tied games – a full replay match.
But penalties are becoming a bigger part of the world game with the controversial introduction of VAR (video assistant referee). The 2018 Russian edition of the World Cup saw a record 29 penalties (excluding shootouts). Of those, 22 were scored – a 76 percent success rate.
As a predictive model, the UQ research is based on statistics – what has worked in the past. And the scientists looked at a complex interaction between the shooter and the goalkeeper.
“Usually, a player’s performance is constrained by biomechanical trade-offs but each player has a range of strategies to overcome these,” says senior author of the UQ study Professor Wilson, from UQ’s Football Research Group. “For example, if a shooter kicks at a high speed, accuracy is decreased, and if a goalkeeper moves early, the probability they’ll move in the correct direction is reduced.”
All players, including international superstars like Lionel Messi and Cristiano Ronaldo, have a range of penalty kick “go-tos” determined by their strengths and weaknesses. The range covers different kicking speeds and areas of the goal at which they aim.
“By taking into account every individual’s range of possible shot speeds, target location, footedness and kicking technique, our model provides a detailed assessment of penalty taking possibilities, and equips players with a range of strategies that can be used against different goalkeepers,” Wilson explains. “For example, a player might have a different strategy against an average goalkeeper that tends to move 200 milliseconds before the ball is kicked compared to a goalkeeper who tends to move later.”
The UQ model is unique in that it takes into account the dynamic between kicker and keeper.
“We wanted to find out how even the best footballers could improve their chances of penalty success,” Wilson adds. “Previous models have often focused either on kickers or goalkeepers independently, but ours examines the strengths and weaknesses of both, making it more accurate and much simpler.”
Wilson highlights the importance of penalties in the modern game as we head into the deciding fixtures of the 2022 World Cup.
“Penalties are the single-most important method of scoring a goal in football – they are the only time in a match where a goal kicker and a keeper are matched one-on-one,” Wilson explains. “Since 1986, 39 per cent of knockout matches in the World Cup finals involved a penalty kick or were decided by a penalty shootout. Better yet, two World Cup finals have been decided by a penalty shootout, in 1994 and 2006.”
“It’s in any coach’s best interests to analyse the strengths and weaknesses of each of their penalty kickers as we have done in our study, to select their optimal strategy. It takes only a few training sessions and could make the difference in a big game.”
Tips for future football stars? The authors write: “Against the average goalkeeper, aiming on the ground toward the centre of the goal is optimal; however, against a late-moving goalkeeper, aiming on the ground to the extremities of the goal is effective.”
Evrim Yazgin has a Bachelor of Science majoring in mathematical physics and a Master of Science in physics, both from the University of Melbourne.
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