# The analytics behind the perfect penalty

After the 2016 summer Olympics, where gold-favorites USA crashed out after a penalty shootout in the quarter-finals against Sweden, the US Women’s National Team’s sporting organization vowed never to lose in this way again. Next major championship they would be prepared. They would take a scientific approach to penalty taking.

The preparation started with data. Football mathematician Tyler Heaps, and his analysis team at the federation — Joris Bekkers and AJ Barnold — collated videos on as many spot kicks as possible from the Women’s game: providing 17,000 data points in total. Heaps said that his team pushed data suppliers to collect as many women’s games data as possible, sending them video and team sheets for international qualifiers. “We tried to automate as much as possible”, he said, “but ended up spending a lot of time on sources trying to collect as much info as possible to be prepared.”

Once the data was collected, the data scientists fit a statistical model on the probability the taker scores depending on where they placed the ball. This is an analysis I have conducted myself, albeit on penalties in the men’s game. The plot below shows the probability of scoring depending on the position of the shot on the face of the goal.

The green zone shows high probability of scoring (100% at the top corners)and blue is lower (50% directly to the keepers left or right).

The most striking aspect of this plot is the large area of green in the top third of the goal. These are areas where shots have almost never been saved. Within the top-left and top-right corners, all penalties placed there result in a goal. These are the perfect, unstoppable penaltie s.

For any penalty taker, understanding this graph is essential. The focus should be on the green areas: to think how to strike the ball to end up at a point where the keeper can’t possibly make a save. For a perfectly struck penalty, it doesn’t matter if the keeper goes the right way. A goal is guaranteed.

# How the US Women National Team applied it in a real game

It was a graph like this which was the starting point for the USWNT new penalty taking strategy. The players were encouraged to eliminate the goalkeeper. This doesn’t necessarily mean blasting in the top corners. The bottom extremities of the goal also offer good alternatives: a low hard spot kick into the bottom corners are also unsavable.

The USWNT players trained penalties with this figure in mind. They found places where they felt comfortable striking the ball and focused on these.

At the World Cup in 2019, when Megan Rapinoe walked up to take the penalty awarded to USWNT just 6 minutes into their last 16 match against Spain, in the quarter-finals, she was well-prepared. And it was the bottom-left hand corner she chose. The Spanish keeper, Sandra Paños, went the wrong way and the USA took the lead.

The real test for Rapinoe, and for the USWNT penalty-taking strategy, came in the 75 th minute. Spain had equalized earlier in the match, so when USWNT were awarded another penalty Rapinoe knew her spot kick was likely to prove decisive, and Paños was unlikely to make the same mistake twice.

Rapinoe gathered speed during her run up and struck the ball hard and placed it in exactly the same spot as the previous spot kick: the bottom left. Paños went the right way this time, but couldn’t reach it. Rapinoe had eliminated the goalkeeper. After the match, she said to Heaps that the penalty “was in the green”.

Tyler Heap’s team also prepared their goalkeepers prior to every game by analyzing likely penalty takers before each match. The chance to prove their method came in the semifinals against England. They had watched Steph Houghton take a penalty in the FA Cup a few months earlier, with a placement that was in the blue, to the goalkeepers right. When Houghton stepped up, she chose the same option again. The goalkeeper, Naeher, went the right way, made the save and the USA went to the final.

Rapinoe scored one more penalty in the tournament, in the final. This time she waited until the Netherlands keeper shifted her weight to go to the left (where her previous goals had been scored) and then shot to the right. The USA had a 100% penalty record at the tournament.

The ‘in the green’ strategy for penalty taking is becoming more widespread as clubs and national teams prepare for tournaments. As one chief data scientist at another leading national team said, “The basic rule is, if you see the keeper go, just put it where the keeper isn’t. If the keeper stands still, hit as hard as possible into the top corner or the extremities of the goal.”

As more coaches and players start to understand the perfect penalty, it is likely that ten or eleven goal penalty shootouts — like the ones we saw between Villareal and Manchester United in the Europa League final last year or between Liverpool and Chelsea in the League cup final in England — will become more common.

It will be interesting to see which national teams are properly prepared for this year’s Euro competition.

Originally published at https://barcainnovationhub.fcbarcelona.com on July 24, 2023.

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Books: Four Ways of Thinking (2023); The Ten Equations (2020); Outnumbered (2018); Soccermatics (2016) and Collective Animal Behavior (2010).