RAlehin: I thought 56… h6 was a mistake, weakening the pawn and opening an avenue towards white’s king, and that bringing white’s light-square bishop to g4 would have been better.
But it only lures black’s rooks away from the main action and steals the g7 square from the black king. And the white’s bishop is way better on the long diagonal, as in the following variations:
59...Rdh8 60. e4 dxe4 61. Nxe4+ Kf7 62. Nxg5+
59...Rdh8 60. e4 dxe4 61. Nxe4+ Bxe4 62. Bxe4 Rd8 63. Rd1 Nxf5 64. Rf3
If black decides not to take on e4, it’s even worse:
59...Rdh8 60. e4 Rxh6 61. Rxh6+ Rxh6 62. e5+ Kf7
followed by f6 no matter where the king goes:
62… Kg7 63. f6+
62. …Kf7 63. f6 Ng6 64. Bxd5+ Bxd5 65. Nxd5
White’s pieces seem to be just in the nick of time everywhere where they should be, whereas black can only sit and defend.
From a human point of view, in such passive positions, sacrificing some material for initiative can bring something, but of course AZ would easily find an antidote for that.