In this situation,why is Ra7 the best?

Sort:
SHENGF

It is black's turn.The computer think Ra7 is best.Can you tell me why?

LaxmiB52
There may be something deeper, but white is threatening Bxf6, leaving the pawn at d5 underdefended.

The knight at c6 is in danger of getting pinned to the rook at a8.
LaxmiB52
If the rook is at a7, the knight is not in danger of getting pinned and it can slide over to the d or e files depending on which is more advantageous after several pieces get swapped
eric0022

The difference in evaluations between moves are actually insignificant. It's better to play a line which you are confident in than to play a computerish winning line which requires immense brain power.

 

I would play any other move like Be6.

LaxmiB52
I doubt I would play a7 either. I was just trying to speculate why this move was considered so highly.
tygxc

Both the natural ...Be6 and the cunning ...Ra7 are equally good.