Why is move 19 not a blunder?

@kindaspongey said in #9:

... As I understand it, in 1916, Tarrasch won a brilliancy prize [for the game where he played 20 c3].
@Forgeron-de-Pion said in #10:
... I don't entirely get what makes it a brilliancy, though.
Alas, I was not present at the 1916 event, so I am unable to shed any light on the thinking of those involved.

Obviously White was already down a Piece & Two Pawns which means Black is already Won & White should be on the Bus Home & have Resigned . there is no compensation so 19 Bh5 isn't the blunder as the Blunder Losing already was played in the past

The evaluation probably went from Minus 6.7 to Minus 8.9

@ThunderClap said in #12:

Obviously White was already down a Piece & Two Pawns which means Black is already Won & White should be on the Bus Home & have Resigned . there is no compensation so 19 Bh5 isn't the blunder as the Blunder Losing already was played in the past

But.. the only other blunder was listed on move 10, and there were inaccuracies which had occurred in between. The analysis after 19 Bh5 goes from -8.8 to -17.0

I honestly think @kindaspongey already wrapped this one up, tbh.

@Forgeron-de-Pion said in #4:

I figured out what you mean, but, that's not a very helpful response.

Okay, try this one on for size then: once the evaluation becomes too lopsided, the engine's conclusions become ever less useful (much less "insightful").

@Forgeron-de-Pion said in #10:

It's still only a two-point difference... and according to stockfish, c3 occurs on the very next move after Rg3+, anyway.

Yeah, I definitely wouldn't call it a blunder. Not even an inaccuracy, both moves are winning. The engine probably likes Rg3+ a little more just because it's more forcing.

I don't entirely get what makes it a brilliancy, though.

Probably because Rg3+ is the "obvious" move and c3 is a quiet move that wins the queen (because it has to guard against mate). But yeah, I agree, it doesn't seem that brilliant.

@ThunderClap said in #12:

...
@Forgeron-de-Pion said in #14:
... I honestly think @kindaspongey already wrapped this one up, tbh.
Just to try to sort things out here: In #6, I was attempting to explain/guess how it came about that the machine did not consider 19 Bh5 (allowing 19...Bxa4) to be a blunder in the Forgeron-de-Pion game. I think that NM ThunderClap was, in effect, saying that the machine was doing the right thing in not calling 19 Bh5 a blunder.
@MrPushwood said in #15:
... once the evaluation becomes too lopsided, the engine's conclusions become ever less useful (much less "insightful").
Useful or not, I think that there is a natural temptation to try to somewhat understand how the machine is making decisions. I believe that, at some time in the past, the machine WOULD have used the word, “blunder”, in connection with a move like 19 Bh5, people made comments somewhat akin to the one by NM ThunderClap in #12, and the programmers got to work making a revision of the software in order to try to come closer to simulating human language usage.
@AsDaGo said in #16:
... Yeah, I definitely wouldn't call [20 c3] a blunder [in the 1916 Tarrasch game]. Not even an inaccuracy, both [20 c3 and 20 Rg3+] are winning. The engine probably likes Rg3+ a little more just because it's more forcing. ...
As I understand it, 20 c3 gave Mieses the chance to go for 20...Qg7 21 Rg3 Qxg3, while 20 Rg3+ Kh8 21 c3 would have allowed Tarrasch to avoid a queen/rook exchange.
@AsDaGo said in #16:
... yeah, I agree, [20 c3] doesn't seem that brilliant.
Maybe nobody could think straight with that Great War going on and everything.

Move #19 is totally Incomprehensible. ~ Swami Vishgoda Svabooti

@kindaspongey said in #17:

As I understand it, 20 c3 gave Mieses the chance to go for 20...Qg7 21 Rg3 Qxg3, while 20 Rg3+ Kh8 21 c3 would have allowed Tarrasch to avoid a queen/rook exchange.

Yeah, true. Both are pretty much the same from a human perspective, but the engine probably gave Rg3 a better score because White gets more material. After Rg3+ Kh8 c3, there is Qe5, but then f4 wins the queen nevertheless. I'm sure Tarrasch saw this, but he probably thought the immediate c3 was simpler.

Which actually brings up a good general point. If you see one line that you're 100% sure you can win, there's no reason going for a more complicated line that might win faster, but you might mess up. Of course, in this case, it's not really clear if c3 or Rg3 is more complicated.

@Forgeron-de-Pion because you were already so bad and defeated in the game, that giving up the Queen doesn't give up the game, it was given much earlier.

It's another inaccuracy, only, in a game full of them.