Can someone explain why this move is a blunder please?

@tpr said ^

As usual the focus is on the wrong move.

He does that often. And he gets quite adamant that you have to follow an obscure, unintuitive robot line that breaks all principles and that is only findable by stockfish or a top GM, if even, on a continuation that never happened in the game, in an idea that you didnt wanted to explore.

Its quite funny.

@jams11
It is and it isnt a blunder. It is a blunder in the sense that you walked into a discovery check, even though there was no immediate punish.

But it isnt a blunder in the sense that the alternative puts you in a seemingly mating net.

Its just that the position is already losing and the win for white is just matter on how good is technique is because that should be a forced win for white if played correctly, regardless if you put resistance or not. Blunder is a relative word when you are lost anyways.

The engine does that from time to time in losing positions. But in reality the game was lost already, when it is at that state, it doesnt matter if you lose in 1, 5 or 25, you never had a realistic chance of winning or drawing once you reached that position.

@Alientcp said in #11:

... And he gets quite adamant that you have to follow an obscure, unintuitive robot line that breaks all principles and that is only findable by stockfish or a top GM, if even, on a continuation that never happened in the game, in an idea that you didnt wanted to explore.

Some actual Alientcp-kindaspongey comments from https://lichess.org/forum/game-analysis/how-was-i-winning-open-game-w-sharp-position :
"... its way more accurate relative to the player strength to measure the position according to activity during the actual play rather than relying on post mortem analysis.
Take for instance this game.
[... [White "Alientcp"] [Black "roybean78"] [WhiteElo "1974"] [BlackElo "1904"] 1 e4 e5 2 Nf3 Nc6 3 Bc4 Nf6 4 d3 Be7 5 c3 O-O 6 O-O h6 7 h3 b6 8 a4 Bb7 9 Be3 d5 10 exd5 Nxd5 11 Nbd2 Nxe3 12 fxe3 Bf6 13 e4 Na5 14 Qe2 Nxc4 15 Nxc4 Re8 16 b4 c5 17 Rad1 cxb4 18 cxb4 Rc8 19 b5 Qe7 20 Qb2 Bxe4 21 dxe4 Rxc4 22 a5 Rb4 23 Qa2 Rxb5 24 axb6 axb6 25 Rd3 Rd8 26 Ra3 Qc5+ 27 Kh1 Qb4 28 Ra7 Qb3 29 Qe2 Qb2 30 Qc4 Qb3 31 Qc7 Rc5 32 Qb7 Qe6 33 Rb1 g5 34 Rxb6 Rd6 35 Rxd6 Rc1+ 36 Kh2 Qc4 37 Rxf6 g4 38 Nxe5 g3+ 39 Kxg3 Qc3+ 40 Nf3 Qc4 41 Qxf7+ Qxf7 42 Rfxf7 Rc6 43 Rfb7 Rf6 44 Ra8+ Rf8 45 Rxf8+ Kxf8 46 Nh4 Ke8 47 Nf5 Kd8 48 Kh4 Kc8 49 Ra7 Kb8 50 Rh7 Kc8 51 Kh5 Kd8 52 Kxh6 Ke8 53 Kg6 Kd8 54 Nd6 1/2-1/2 ...]
I was down material by move 20, but I didnt wanted to trade to seek some activity, else it was a lost game.
I ended up in a winning position, and I messed it up with a premove due to time trouble. If I had thought 1 more second on that last move I would have won. I know how to convert, its quite easy. But people mess up, and the engine eval is irrelevant as it did not accounted for stupid moves.
My activity alone was not even enough to give me a + position until he messed up, which is what I was waiting for and got.
The eval of the engine is useless for me. I knew I was losing. Then I knew I was clearly winning and he couldnt do anything about it to prevent me from doing so. Neither of those happened. ..." - Alientcp (#14)

"... When a machine says something like '~x', it is not even attempting to say anything about the strength of the specific players and the continuation they will produce. The machine is being made available to help people to try to IMPROVE for the future. The hope is that it is describing possibilities that one might want to try to learn to produce. ... Consider the position after ... 8 a4 Bb7, which the machine evaluates as '+0.6'. After you chose 9 Be3, the evaluation dropped to '-0.3'. That is a signal that you could have made a better choice at that point. After 9 Be3 d5 10 exd5 Nxd5, you had nothing better than 11 Nbd2. If, instead of 9 Be3, you had played 9 Re1, you would have been able to react to 9...d5 10 exd5 Nxd5 with 11 Nxe5. ... don't you think that you could learn from the machine calling your attention to missed opportunities such as 9 Re1 ? ..." - kindaspongey (#15)

([Site "https://lichess.org/dNeYi5qu"])

@Alientcp said in #11:

... @jams11 ... in reality the game was lost already, when it is at that state, it doesnt matter if you lose in 1, 5 or 25, you never had a realistic chance of winning or drawing once you reached that position.

Is it really possible to be confident about what could have happened after beobeo0209 played 31 Bf3+ ("2.99 --> 2.21")?
In that [TimeControl "480+0"] game, beobeo0209 ([WhiteElo "1189"]) also made these choices:
"5. g4?? (3.40 --> -0.30) Blunder."
"12. Ne2?? (3.38 --> 1.16) Blunder."
"13. c3?? (2.86 --> 0.84) Blunder."
"18. cxd4?? (3.00 --> -2.20) Blunder."
"23. O-O-O?? (4.43 --> 0.25) Blunder."
"25. Bf7?? (5.52 --> -0.58) Blunder."
"33. Qc7?? (6.19 --> 2.55) Blunder."
([Site "https://lichess.org/kejChU6k"] [Annotator "lichess.org"])

And he gets quite adamant that you have to follow an obscure, unintuitive robot line that breaks all principles and that is only findable by stockfish or a top GM, if even, on a continuation that never happened in the game, in an idea that you didnt wanted to explore.

If you read that thread, what I described is exactly what happened lol. Focused in an unintuitive robot line that broke principles, never happened, that I didnt even wanted to consider (because again, broke principles) because the continuation I chose led to a lost pawn 10 moves after. The robot continuation is hard to find because no one thinks like the robot, and in the actual continuation, no normal player would have seen 10 moves ahead in a 5 minute game. Maybe an IM or GM would have seen it.

The comment was quite accurate.

Move 76 is pure evil imo

@Alientcp said in #11:

... And he gets quite adamant that you have to follow an obscure, unintuitive robot line that breaks all principles and that is only findable by stockfish or a top GM, if even, on a continuation that never happened in the game, in an idea that you didnt wanted to explore. ...

@kindaspongey said in #12:

... Some actual Alientcp-kindaspongey comments from https://lichess.org/forum/game-analysis/how-was-i-winning-open-game-w-sharp-position :
"... its way more accurate relative to the player strength to measure the position according to activity during the actual play rather than relying on post mortem analysis.
Take for instance this game.
[... [White "Alientcp"] [Black "roybean78"] [WhiteElo "1974"] [BlackElo "1904"] 1 e4 e5 2 Nf3 Nc6 3 Bc4 Nf6 4 d3 Be7 5 c3 O-O 6 O-O h6 7 h3 b6 8 a4 Bb7 9 Be3 d5 10 exd5 Nxd5 11 Nbd2 Nxe3 12 fxe3 Bf6 13 e4 Na5 14 Qe2 Nxc4 15 Nxc4 Re8 16 b4 c5 17 Rad1 cxb4 18 cxb4 Rc8 19 b5 Qe7 20 Qb2 Bxe4 21 dxe4 Rxc4 22 a5 Rb4 23 Qa2 Rxb5 24 axb6 axb6 25 Rd3 Rd8 26 Ra3 Qc5+ 27 Kh1 Qb4 28 Ra7 Qb3 29 Qe2 Qb2 30 Qc4 Qb3 31 Qc7 Rc5 32 Qb7 Qe6 33 Rb1 g5 34 Rxb6 Rd6 35 Rxd6 Rc1+ 36 Kh2 Qc4 37 Rxf6 g4 38 Nxe5 g3+ 39 Kxg3 Qc3+ 40 Nf3 Qc4 41 Qxf7+ Qxf7 42 Rfxf7 Rc6 43 Rfb7 Rf6 44 Ra8+ Rf8 45 Rxf8+ Kxf8 46 Nh4 Ke8 47 Nf5 Kd8 48 Kh4 Kc8 49 Ra7 Kb8 50 Rh7 Kc8 51 Kh5 Kd8 52 Kxh6 Ke8 53 Kg6 Kd8 54 Nd6 1/2-1/2 ...]
I was down material by move 20, but I didnt wanted to trade to seek some activity, else it was a lost game.
I ended up in a winning position, and I messed it up with a premove due to time trouble. If I had thought 1 more second on that last move I would have won. I know how to convert, its quite easy. But people mess up, and the engine eval is irrelevant as it did not accounted for stupid moves.
My activity alone was not even enough to give me a + position until he messed up, which is what I was waiting for and got.
The eval of the engine is useless for me. I knew I was losing. Then I knew I was clearly winning and he couldnt do anything about it to prevent me from doing so. Neither of those happened. ..." - Alientcp (#14)

"... When a machine says something like '~x', it is not even attempting to say anything about the strength of the specific players and the continuation they will produce. The machine is being made available to help people to try to IMPROVE for the future. The hope is that it is describing possibilities that one might want to try to learn to produce. ... Consider the position after ... 8 a4 Bb7, which the machine evaluates as '+0.6'. After you chose 9 Be3, the evaluation dropped to '-0.3'. That is a signal that you could have made a better choice at that point. After 9 Be3 d5 10 exd5 Nxd5, you had nothing better than 11 Nbd2. If, instead of 9 Be3, you had played 9 Re1, you would have been able to react to 9...d5 10 exd5 Nxd5 with 11 Nxe5. ... don't you think that you could learn from the machine calling your attention to missed opportunities such as 9 Re1 ? ..." - kindaspongey (#15) ...

@Alientcp said in #13:

... If you read that thread, what I described is exactly what happened lol. Focused in an unintuitive robot line that broke principles, never happened, that I didnt even wanted to consider (because again, broke principles) because the continuation I chose led to a lost pawn 10 moves after. The robot continuation is hard to find because no one thinks like the robot, and in the actual continuation, no normal player would have seen 10 moves ahead in a 5 minute game. Maybe an IM or GM would have seen it.

The comment was quite accurate.

I guess the #13 version of accuracy involves saying "focused in"
instead of the #11 language, "gets quite adamant that you have to follow".

I guess everyone can look for themselves ([Site "https://lichess.org/dNeYi5qu"] [White "Alientcp"]) at the position after
1 e4 e5 2 Nf3 Nc6 3 Bc4 Nf6 4 d3 Be7 5 c3 O-O 6 O-O h6 7 h3 b6 8 a4 Bb7
and decide whether or not 9 Re1 d5 10 exd5 Nxd5 11 Nxe5 is "an obscure, unintuitive robot line that breaks all principles and that is only findable by stockfish or a top GM, ..." (#11).

The machine did not seem to believe that Alientcp's choice, 9 Be3, necessarily led to a lost pawn.
Indeed, it evaluated the post-9 Be3 position as only ~0.3 in favor of roybean78 (Alientcp's opponent).
As far as I can tell, the pawn was only lost after Alientcp's choice of 20 Qb2 instead of 20 Ne3.