IT LOOKS easy: a shot from just 11 metres (36 feet) out, with only the goalkeeper to beat. But even the very best footballers miss a meaningful share of penalties, which are awarded for infringements within the opposition box or used to decide tied matches in knockout competitions. Lionel Messi, perhaps the most accomplished finisher in the sport’s history, blazed an attempt over the bar in the final of last year’s Copa América, the main prize for South American countries. Cristiano Ronaldo, another contender for the title of best-ever forward, had hammered one against the post in the European Championship a week before.

In spite of a few high-profile misses, both of these all-time greats have impressive records from the spot. In the past ten seasons of league games, Mr Ronaldo has converted 87% of his efforts (66 of 76) and Mr Messi has succeeded with 84% (46 of 54). The overall rate for La Liga, the Spanish division in which both men ply their trade, has been 77%. Though a league-average penalty-taker might equal the success of these men just by sheer luck, he would only have a 10% chance of matching Barcelona’s diminutive Argentine, and just a 3% hope of emulating Real Madrid’s Portuguese powerhouse.

Yet staying ahead of the field is hard to do. In our analysis of the 2,788 penalties taken in the past decade in La Liga, the English Premier League and Germany’s Bundesliga, we found no statistically significant relationship between a player’s past performance and his subsequent success. If that seems hard to believe, consider the fact that Mr Messi found the net 93% of the time in the first half of his sample, but just 78% of the time in the remainder. Mr Ronaldo endured a similar slump: his miss in the European Championship was the fifth in his last eight across all competitions. Other players rebound after a slow start. Wayne Rooney, England’s captain, scored a measly 64% in the first half of our sample, followed by a more respectable 85%.

This does not prove that the outcome of a penalty is completely random. Data about the placement of shots are scarce, but they might be a better predictor of future outcomes. And at least a handful of players have seemed to show a knack for it: the most famous is Southampton’s Matt Le Tissier, who converted 48 of his 49 spot-kicks. Even if 1,000 league-average players were given that many opportunities, there is a 93% chance that none of them would equal his record.

Nonetheless, in most cases, the data are too noisy to tell the good shooters from the merely fortunate ones. It would make sense for Frank Lampard and Steven Gerrard, the highest-scoring midfielders in the history of the Premier League, to be lethal from the spot. In practice, however, the large number of penalties they converted was mostly a function of opportunity. Given as many chances as they had, a mediocre taker could easily have fluked his way to similar heights.