Well, let's follow the line given - which is sub-optimal for both sides - for a moment.

1.Bc4 (white needs to finish his development before he attacks) a6 2.0-0 b5 Be2 3.Rd2 Nc6 4.Rfe1

Black is completely busted. White is threatening to win a queen and N for two rooks. Black can try to defend by exchanging:

4. ... Qxg6 5.Nxg6! 0-0-0

is black out of the woods? No!

6.Nxh7 Rh8 7.Bxd8 - white's won an exchange, with more coming (he'll play Ng5 and Nf7, removing the defender of d7, and on Nxe5, f4 resumes the threat).

So black's queenside expansion plan doesn't work. What else does he have?

1. Bc4 Nc6 2.Qxd8 Nxd8 3.Ng5 h6 (plausible, but loses. No better is Rh8 4.Ne4 Nc6 5.Nd6+ Kf8 6.Nxc8 & Rxd7) 4.Nh7 Rh8 5.Nf6 with a rout on.

1.Bc4 h6 can't possible be a good move for black. He weakens his position, gives up a pawn, and ... well, let's see.

1.Bc4 h6 2.Qxh6 Qa5 3.Qd2 Nd5 4.0-0 (you must finish your development before you attack) N7b6 5.Qg5! and black has no good defense against the combined threats on d8 and e7. (The sacrifice Rxd5, followed by Qe7#, hangs in the air).

In that line, my computer offers 4. ... Qa4 instead, but that doesn't look much better. 5.Qd8 Nc6 6.0-0 (must get your own king to safety - this also allows your second rook to get involved) a6 (with dreams of b5) 7.Bxe6! fe 8.Qxg6+ (this is a very thematic sacrifice) Rf7 9.Qxe6+ (three pawns for the pieces ... and not done yet) Ne7 (Kf7 10.Qh6+ and e6 wins back the piece) 10.Bxe7 Rxe7 11.Qg6+ and e6.