Every football fan will know that sinking feeling: an opposition player has the ball
in your box but is heading nowhere. The defence are perfectly situated. The attacker is being
forced into a worse position. There is almost no chance of a goal being scored.
But then it happens: A foot comes in, the attacker stumbles and falls,
and the referee points to the penalty spot.
These moments highlight the injustice of the penalty kick. From a situation
where it seemed impossible that a team could score,
they’re now in a situation where they are more likely to score than not.
These sorts of situations raise an important question: are penalties overpowered?
With the rise of data analytics in football,
we can now show how overpowered penalties are in the modern game.
Expected goal models allow us to predict with a degree of certainty the likelihood of scoring
chances both from the penalty spot but also from open play. As things stand, the likelihood of
scoring a penalty in the Premier League is around 78% or 0.78 expected goals. This means that,
in around 8 out of 10 instances, you would expect a Premier League footballer to score a penalty.
Expected goals models can also give us a good idea of how likely teams are to score from open play.
Although there are a number of different variables that need to be taken into account
when calculating the expected goal value of a chance, the most important factor is shot
location. If we use this information to build a base map for expected goals from open play, you’ll
see that the closer you are to goal when you take your shot, the more likely you are to score:
Notably, the best chances from open play are those closest to the goal and
even they are given an expected goal value of around 0.6 or a likelihood
of scoring around 60% - less than the 78% likelihood of scoring a penalty.
We can compare this base map with a plot which shows the area where
penalties were most likely to be won in the Premier League between 2011 and 2022:
As you can see, penalties are most likely to be won from an area further from the goal than
the penalty spot and to the left hand side. Matching this location to the expected game
base map puts this location in an area where you might expect to score less than 20% of the time.
Such an incident would see an increase in scoring potential
of around 60% meaning that you're around four times more likely to
score from a penalty than you are from the open play location where the penalty is won.
But this increase is only for the most common area where penalty kicks are won. If we’re looking at
the increase for the average penalty kick, it gets even worse. The Athletic’s John Muller
has shown that in half of the instances where penalty kicks were won in the Premier League
between 2011 and 2022, the likelihood of scoring before the penalty was given was less than 6%.
On top of this, Muller found that only 1 in 20 possessions that end in a penalty had a better
than 19% chance of being scored from the last known ball location. If you win a penalty, then,
you’re almost always improving your chance of scoring by about four times or more.
And penalties aren’t just overpowered in terms of raising a team’s likelihood of scoring. They
also impact a team’s likelihood of winning games. Using the same dataset of Premier
League games since 2011/12, John Muller was also able to show that over half of all penalty calls
change the current result of the game either from drawing to winning or losing to drawing.
Are penalties overpowered? Undeniably. In almost every situation where you win one,
you are more likely to score than you were before it was given. And in
over half of the situations where you win them, the outcome of the game is changed.
But although we have better explanations for why penalties are overpowered, criticism of penalty
kicks has a long pedigree. Even back in the early 1900s, there were debates about how the
rule might have been changed, particularly in America, where there was perhaps less
conservatism about the rules of a game that had been developed across the Atlantic Ocean.
In 1913, the Philadelphia Inquirer noted that, “There are many progressives… who
favour changes in the rules and who are inclined to the belief when it should be
changed notwithstanding that England and other countries where soccer has been played for a
much longer time than it has here have found the rule good enough for them.”
In the same article, a rule change was submitted by a couple of readers who
suggested that the penalty area could be decreased to “a semi-circle from the
outside lines of the goalkeeper’s area to a point 18 yards from the goal line.”
This tradition of penalty area scepticism has continued within the United States. For
a period in the 70s in the NASL and for the first four seasons of MLS,
both leagues implemented a form of “running penalty,” which saw penalty takers running
towards the goal from the halfway line and attempting to beat the keeper to score.
The argument given was that these running penalties were more entertaining than traditional
penalty shoot outs but, importantly, the odds of scoring a penalty for those four early seasons
of MLS was around 45% - higher than the odds of scoring in most situations leading to penalty
kicks but much lower than the 78% likelihood of scoring a penalty in the Premier League.
As things stand, the penalty kick is here to stay. But as people start to recognise
just how overpowered they are, perhaps we will see the appetite for a rule change.