Your worst move is not a flail from a lost position. It is played by the person who is winning. For the typical player, 56.9% of blunders come from a position they were already winning, against 13.2% from one they were already losing, and it holds for every player measured.

Your worst move is not a flail from a lost position.

It is played by the person who is winning. For the typical player, 56.9% of blunders come from a position they were already winning, against 13.2% from one they were already losing, and it holds for every player measured.

Better means at least a pawn up by the engine at the moment the move was played, worse at least a pawn down. The worst move of a typical game is not a flail from a lost position. It is played by the person who was winning. Each percentage is the median across players, so no single prolific account can carry the finding.

Across 308,121 analysed games from 245 players.

The Position

Black to move and win.

Black to move · rated 1531.

The answer runs in tomorrow's issue.

Eloist puzzle deck

The Opening Files · No. 3

The later you blunder, the more it costs you.

A player's worst move is worth about four and a half pawns in the opening stretch of a game. By the closing stretch of the same game it is worth about eight pawns, a rook and a bishop instead.

Walk a game from start to finish in five stages and the damage climbs at every one: about four and a half pawns in the opening stretch, then more, then more again, until the last fifth costs about eight pawns, a rook and a bishop. It is not simply that long games contain more mistakes. The same mistake is worth more when it arrives late, because by then there is less position left to recover in and usually less clock to find the recovery with.

Across 361,587 analysed games from 247 players.

The Opening Files runs again tomorrow.