Evaluation as important as calculation

In this game I was playing Black.
I have recently begun to appreciate the importance of evaluation of positions. Especially in the openings, one must aim for no more than equality as Black. This is what I aimed for in the present game. The move ... Nb6 is the key one. I had intended a different continuation, but spotted that White was aiming for b4, weakening the c4 square. I can't explain why he played the move anyway, but the consequences were pretty severe. But what if White had played something other than b4. Would ... Nb6 still be justified?

You played well. Even if white plays 12 b3 your move 11...Nb6 was justified, as it allows you to develop your Bc8. You already had the upper hand: Re8 on the open file, grip on central square e4. His 8 g3 was no good. a fianchetto bishop is not strong if it stares at a pawn chain b7-c6-d5. His 11 Rb1 was no good either, as you kick it with ...Bf5. Good game.