why was 36. ... Qa6 played ...

[pilgrimdan]

[Event TCEC16]
[Site ""]
[Date "2019.9.21"]
[Round ""]
[White "Leela"]
[Black "KomotoMCTS"]
[TimeControl "-"]
[Result "1:0"]

1.c4 c6 2.Nf3 Nf6 3.d4 d5 4.e3 a6 5.Bd3 Bg4 6.Nbd2 Nbd7 7.Qc2 e6 8.b3
Bd6 9.O-O Bh5 10.Bb2 Qc7 11.c5 Be7 12.g3 a5 13.a3 O-O 14.b4 Bg6 15.Bxg6
hxg6 16.Bc3 axb4 17.axb4 Rfb8 18.Kg2 Ne8 19.Rab1 Qc8 20.h4 Nc7 21.Rh1
Nb5 22.Rbe1 Na3 23.Qc1 Nb5 24.e4 Qf8 25.Qc2 Na3 26.Qd3 Nb5 27.Bb2 Nc7
28.Bc1 b6 29.e5 Na6 30.Ba3 Nc7 31.Bc1 Ra4 32.Ng5 bxc5 33.bxc5 Rbb4
34.Ndf3 Bxg5 35.hxg5 Qa8 36.Qe3

[d]q5k1/2nn1pp1/2p1p1p1/2PpP1P1/rr1P4/4QNP1/5PK1/2B1R2R b - - 0 36

36. … Qa6? (Ne8 looks better)

37.Qf4 Kf8 38.Rh8+ Ke7 39.Qf6+ Nxf6
40.exf6+ gxf6 41.gxf6+ Kxf6 42.Bg5+ Kg7 43.Reh1 Qf1+ 44.Rxf1 Ra8 45.Rxa8
Nxa8 46.Ra1 Nc7 47.Be3 Rb7 48.g4 g5 49.Bxg5 f6 50.Be3 Nb5 51.g5 fxg5
52.Bxg5 e5 53.dxe5 Nc7 54.Bf6+ Kg6 55.Nd4 Rb4 56.Nxc6 Rc4 57.Ne7+ Kf7
58.Ra7 Ne6 59.c6 d4 60.Nf5+ Kg6 61.Nh4+ Kh6 *

[leavenfish]

...Ne8 is bad too...has no purpose whatsoever frankly - can't imagine why you think it is 'better'. The position is just bad for Black and there are no good moves. So, the short answer is 'it doesn't matter'.

But 'why'? I presume it is something as simple as...the engine seeing nothing preventing the position from getting even worse and it just gives the Queen more squares to move to and leaves Nc7 with more squares to move to (b5, hitting d4 for example). But that may just be me bringing a human eye to it.

[pilgrimdan]

...Ne8 is bad too...has no purpose whatsoever frankly - can't imagine why you think it is 'better'. The position is just bad for Black and there are no good moves. So, the short answer is 'it doesn't matter'.

But 'why'? I presume it is something as simple as...the engine seeing nothing preventing the position from getting even worse and it just gives the Queen more squares to move to and leaves Nc7 with more squares to move to (b5, hitting d4 for example). But that may just be me bringing a human eye to it.

doesn't 36. ...Ne8 prevent the Q sac that occurs by white on move 39?

[leavenfish]

No idea, but position bad enough to be considered 'lost'...is lost, whatever you play.