The substitute who changed the game

A coach made the same substitution in eleven matches and the team scored shortly afterwards in seven of them. The press called it a tactical signature. The coach, asked about it, said the substitution usually happened around the seventieth minute.

That answer contains the whole analysis. Goals are not spread evenly through a match; the final twenty minutes produce substantially more of them than the first twenty, because defenders tire, lines stretch and teams that are behind take risks. A substitution made at the seventieth minute will therefore be followed by a goal more often than one made at the twentieth, whoever comes on.

Separating the effect of the change from the effect of the moment requires a comparison that nobody watching a match can make: what would have happened at the seventieth minute without the substitution. Analysts build it from thousands of matches, and when they do, most substitution 'effects' shrink towards the base rate for the period. Some survive, and the ones that survive tend to involve a specific mismatch rather than fresh legs in general.

None of this means substitutions do not matter. It means the evidence a spectator has access to cannot distinguish a good decision from a well-timed one, and the two feel identical.

The habit worth taking from it applies well beyond football. Whenever something is followed by a result, ask what else was true at that moment. If the thing reliably happens at a time when the result is already more likely, the sequence is not evidence of a cause, however many times it repeats.