user20092: [Event "the_meayhi vs. oxygen2020"]
[Site "Chess.com"]
[Date "2020-08-16"]
[White "the_meayhi"]
[Black "oxygen2020"]
[Result "1-0"]
[WhiteElo "810"]
[BlackElo "1032"]
[TimeControl "blitz"]
[Termination "the_meayhi won by resignation"]
[fen ""]

1. d4 d5 2. Bf4 c5 3. dxc5 e6 4. Bxb8 Rxb8 5. e3 Bxc5 6. Nc3 Ne7 7. Nf3 Bd6 8. Qd4 O-O 9. Bd3 a6 10. Qh4 g6 11. Ng5 h5 12. g4 Nf5 13. Bxf5 1-0

Despite the result of the game, te chess.com engine says that White blundered. It also says that one player was winning and blundered it away. What do those mean?


user8673: 13.Bxf5?? is a blunder because 13.gxf5 wins a piece. In other words, by playing 13.gxf5! White has a winning game. When the computer detects a big change, like a change from an even or near even game to a winning/losing game, it considers the move that caused the change to be a blunder.

user18809: Your last move 13.Bxf5 leaves you with a much smaller advantage than 13.gxf5, that's what the engine is counting as a "blunder" (some of the previous moves have smaller mistakes, but none of them should be counted as "blunders")

20092: <pre><code>[Event &quot;the_meayhi vs. oxygen2020&quot;]
[Site &quot;Chess.com&quot;]
[Date &quot;2020-08-16&quot;]
[White &quot;the_meayhi&quot;]
[Black &quot;oxygen2020&quot;]
[Result &quot;1-0&quot;]
[WhiteElo &quot;810&quot;]
[BlackElo &quot;1032&quot;]
[TimeControl &quot;blitz&quot;]
[Termination &quot;the_meayhi won by resignation&quot;]
[fen &quot;&quot;]

1. d4 d5 2. Bf4 c5 3. dxc5 e6 4. Bxb8 Rxb8 5. e3 Bxc5 6. Nc3 Ne7 7. Nf3 Bd6 8. Qd4 O-O 9. Bd3 a6 10. Qh4 g6 11. Ng5 h5 12. g4 Nf5 13. Bxf5 1-0
</code></pre>
<p>Despite the result of the game, te chess.com engine says that White blundered. It also says that one player was winning and blundered it away. What do those mean?</p>
<p><a href="https://i.stack.imgur.com/PUGh2.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/PUGh2.jpg" alt="engine" /></a></p>
 8673: <p>13.Bxf5?? is a blunder because 13.gxf5 wins a piece. In other words, by playing 13.gxf5! White has a winning game. When the computer detects a big change, like a change from an even or near even game to a winning/losing game, it considers the move that caused the change to be a blunder.</p>
 18809: <p>Your last move <strong>13.Bxf5</strong> leaves you with a much smaller advantage than <strong>13.gxf5</strong>, that's what the engine is counting as a &quot;blunder&quot; (some of the previous moves have smaller mistakes, but none of them should be counted as &quot;blunders&quot;)</p>
