Risk Aversion: A Story of Penalty Kicks
Popularized by the likes of Moneyball and FiveThirtyEight, sabermetrics refers to the use of data in sports decision-making. As a loud-and-proud sports fiend myself (though I despise watching baseball), I love sports data. Though sabermetrics relates specifically to baseball analytics, the analytics revolution has been brought to most other sports as well. Economists — as they are wont to do — have entered the field en masse and now produce very many wild results ranging from the incendiary cheating in sumo wrestling to gender discrimination in chess (the latter made watching The Queen’s Gambit even more exciting, though, of course, Beth Harmon is fictional). This blog begins a 1 of n part series on sports analytics in which I will attempt to humorously connect many different topics and entertain my minimal audience of one (1), two (2) including myself. Most likely, the endeavor will fail, though that is no reason to stop.
The cardboard box manufacturing industry is worth about $75 billion dollars in the US. The aggregate economic production of all sports in the US is…$73 billion dollars. And yet, I am yet to meet a single person who cares more about cardboard boxes than sports—though to be fair, I have not met many people working in box manufacturing. People weirdly, bizarrely, disproportionately care about sports. With ups-and-downs, ins-and-outs, hope and despair, sports are a microcosm of life. And with that, I begin my series on sports.
Part I: An Introduction to Kicking Down the Middle
While watching the UEFA Euro Cup recently, I’ve been shocked by the number of missed penalty kicks (PKs). At one point in the tournament, everyone other than Cristiano Ronaldo (3/3) was 5/12 on PKs, which are by far the easiest way to score in soccer with an overall success rate of around 75%. To understand PK strategy, the important thing to note is that the ball can travel up to 125 miles per hour which means after leaving the boot, it can theoretically enter the net in under two-tenths of a second. For the goalie, the velocity of the ball necessitates having to guess where the ball is going before it is kicked. So, they just dive (pseudo)randomly. If they guess correctly, they might block it. If they guess incorrectly, they are almost certain not to save it, though the kicker still might miss the goal (e.g. wide or high).
The thing that has always surprised me was the fact that no goalies ever stay in the middle — as in, they don’t dive to either side — and kickers never kick down the middle. Clearly, there is some non-optimizing voodoo going on here. See the table below from Chiappori, Levitt, & Groseclose (2000).
Focusing on the bottom row, to maximize the chance of success (independent of goalie movement), kickers should kick down the middle — at least more frequently than they do right now. Down the middle is a far better strategy — even a 5 percent improvement is non-trivial when it comes to high-stakes shootouts — than kicking left or right.
And yet, no one kicks down the middle. Why may this be? The main hypothesis revolves around our good old friend: risk aversion. As a professional player if your kick gets saved after you kicked left, you at least used your decades of soccer training to make a good kick. If it gets saved after kicking down the middle, you look like an absolute BUFFOON. And so to avoid this shameful possibility, soccer players don’t kick down the middle. It’s exactly the same reason most of us — a general group in which I am most certainly included — so vehemently try to avoid downside risk. All those motivational quotes try and get us to take risks. Michael Scott said Wayne Gretzky said “You miss 100 percent of the shots you don’t take.” But in reality, if I miss one of those shots, I will be wildly embarrassed. See two of my favorite epic humiliation moments below:
Just, embarrassing.
Part II: Dance Moves
This brings me to the next section: Liverpool & Grobbelaar. In 1984, Liverpool was in the European Cup (today’s Champions League) Final against the famed Roma Club. The game was in penalties. Up to that point in his career, Grobbelaar — Liverpool’s goalie — had always had standard goal-saving technique. Dive this way or that. (Pseudo)randomly. Until now. He started dancing in the goal during the kickers’ run-ups. What nerves of steel! He could have made a complete fool of himself, but instead, he affected the kickers to such a degree that they just flat-out kept missing the goal:
The original stanky leg. Highly effective.
In 2005, Liverpool (miraculously) found themselves back in the Champions League final. They were down 3-0 at halftime to AC Milan, another (much better) Italian team. And yet, they roared back and took the game to penalties. Since Grobbelaar by this point was rather old, they had to have a new goalie: Jerzy Dudek. A Polish son of a coal miner born in a very small town, Dudek was relatively unknown growing up, given he was going to become Liverpool’s goalie one day. Though of course he—nor anyone else—knew this would happen. It’s a true rags-to-riches story. In penalties, the Liverpool captain told Dudek to remember back to Grobbelaar’s ‘wobbly (stanky) legs.’ Prior to this, Dudek had always had traditional PK form (just guess and dive). But he started dancing. His wife said, later, that she could not recognize her husband:
Never really knew that (s)he could dance like that!
Part III: A Quasi-Related Story
Chak de India was one of my favorite movies growing up. It’s a (completely fictional) story about the Indian Women’s National Hockey Team winning the World Cup as complete under-dogs. Their coach is played by none other than Shah Rukh Khan — no surprises there for any Bollywood fans out there — who happens to be a disgraced former Indian player. Reason for his disgrace? Missing a penalty (he didn’t shoot middle). To add insult to injury, the missed penalty came against…Pakistan (this is highly problematic for an Indian audience). The climactic scene — which is, of course, yet another dramatic penalty shoot-out — is from the final of the Women’s World Cup.
Key Takeaway: Shoot Middle — but at your own risk. I’m looking at you, Mbappe.
