How to win a penalty shootout (with game theory)

Lionel Messi — the top World Cup scorer of all time — is a below-average penalty kicker, and Planet Money argues that's because penalties aren't really a kicking contest. They're a game-theory problem. Host Jeff Guo brings in the Soccernomics podcast team to explain the 'mixed strategy': elite kickers deliberately shoot to their weaker side some of the time, in a genuinely random pattern, because a predictable shooter is a stopped shooter. Goalkeepers are running the identical calculation in mirror image, deciding which way to dive before the ball is even struck.

The centerpiece is the story of economist Ignacio Palacios-Huerta, who spent years building the world's best database of penalty habits — with his wife and mother mailing him videos from Spain — while clubs tracked nothing. Chelsea hired him before the 2008 Champions League final against Manchester United, and his crib sheet worked eerily well: goalkeeper Petr Cech followed it to stop Cristiano Ronaldo. But Chelsea's kickers all aimed at the same spot he'd identified, United's keeper spotted the pattern mid-shootout and literally pointed it out to the final kicker, and the rattled Nicolás Anelka hit exactly the shot the report said never to take. The data was right; using it predictably lost the final anyway.

The episode closes with how thoroughly this research has remade the sport: goalies tape crib sheets to their water bottles, teams pipe fake crowd noise into practice shootouts, and the classic 60% advantage of shooting first may have evaporated now that everyone comes armed with a report.