Originally Posted by
John Upper
One possibility is that the chess.com engine is either too weak or too slow to provide accurate evals. For instance, in the game you posted, 13.Nc3 is not a blunder (White is already lost), but after 13.Ne6 Ne2+ IS a blunder. Instead, Black should play 13...Nf3, which forces mate.
Another possibility for the wildly swinging evals on chess.com is that they may be using the Komodo MonteCarlo engine, which gives evals based on its estimate of the probability of winning given many different possible continuations, rather than on the results of best play from both sides (as the traditional AB engines like Stockfish do).
BTW, the line you played to win was analyzed in Tartakower's book 500 Master Games, or you might have previously seen the game below, which is the earliest one in ChessBase:
[Event "St Petersburg"]
[Site "St Petersburg"]
[Date "1874.??.??"]
[Round "?"]
[White "Knorre, Victor"]
[Black "Chigorin, Mikhail Ivanovich"]
[Result "0-1"]
[ECO "C50"]
[PlyCount "28"]
[EventDate "1874.??.??"]
[EventType "game"]
[EventRounds "1"]
[EventCountry "RUS"]
[SourceTitle "EXT 2011"]
[Source "ChessBase"]
[SourceDate "2010.11.26"]
[SourceVersion "1"]
[SourceVersionDate "2010.11.26"]
[SourceQuality "1"]
1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. O-O Nf6 5. d3 d6 6. Bg5 h6 7. Bh4 g5 8. Bg3
h5 9. Nxg5 h4 10. Nxf7 hxg3 11. Nxd8 Bg4 12. Qd2 Nd4 13. Nc3 Nf3+ 14. gxf3 Bxf3
0-1