Blunder of the week

Okay.

So I haven't been around here very long, and I can barely claim to be 600 on a good day. Even so, I have seen- and committed- some truly boneheaded maneuvers. This, however, takes the cake. I was playing black against a fellow 600, and getting kicked around pretty badly. On turn 17, we wound up in this position:

As you can see, it's looking pretty grim. I'm down a knight and bishop, my pawn structure is a mess, and there's checkmate threats everywhere. Now, I ask you: what is white's WORST possible move? How can he take a position like this, and blunder the entire game? 

Any ideas? Anybody? How about this:

White CASTLES QUEENSIDE! I swear to god, I wanted to scream at him through the internet. Because now, there's Qxa2, bringing a massive threat right to the King's backdoor. Even then, the game's not over, because Qxe6 forces me to capture his queen with my own, after which Re1, Kf7, Rxe6, Kxe6 wins back the queen at the cost of a rook. But instead, he plays Pe7. Don't ask me why. I, of course, play Qa1+, and instead of Kd2 (salvageable position, though he'd lose his queen in two moves), he plays Kc2, leading to checkmate with Qxb2.

Sheesh...

Moral of the story: the beginner's advice to "Castle early, castle often" is bunk. Castling is a strategic decision like any other, and the risks don't always outweigh the rewards. Indeed, there are several chekmates much more likely after castling. The classical back-row checkmate, the protected Qxb2, and the backdoor attack from the opposing rook are just a few that come to mind. Don't castle just because you can, and don't castle purely to develop the rook swiftly. Watch the ENTIRE board, and remember that every game is different.

Yeah sometimes you have to break some rules.