Opening Leak Lab

Ruy Lopez: Morphy Defense

C78 1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. O-O b5 6. Bb3 d6

Black scores 48.4% here across 451 club games — but the 26.8% who answer b5 score 37.2%, 11 points worse.

What Black actually plays here

Across 451 games from a Lichess-derived book of club play, Black scores 48.4% in this position. These are the replies people choose, and how each one works out.

ReplyGamesShare Black scoresVerdict
Be7 207 45.9% 60.1% holds up
b5 121 26.8% 37.2% below the line
Nxe4 63 14.0% 46.8% holds up
d6 34 7.5% 32.4% below the line

"Below the line" means the reply scores at least three points worse than the position does overall. Replies played fewer than 25 times are left out: the sample is too small to read.

Is this costing you anything?

A table of averages cannot tell you whether you go wrong here — only your own games can. Opening Leak Lab reads your Chess.com or Lichess archive, finds the decisions you repeat, and checks each one against this book and a bundled Stockfish.

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