Usually chess puzzles at my level (beginner) have just one or two forced variations and a clear achievement, like a substantial material gain or checkmate. Once in a while, though, a puzzle leaves me wondering, why the solution is actually supposed to be such a good thing.
The following puzzle is from Susan Polgar's and Paul Truong's book "Chess Tactics for Champions", #11 from the chapter on trapping. White to move:
[White "Puzzle by Susan Polgar"] [Black "Trapping: #11"] [Result "*"] [FEN "2rr2k1/p3bpp1/1p2pn1p/2p5/8/2P1PPB1/PP2B1PP/R4RK1 w - - 0 1"]
The solution is:
This example demonstrates well the power of the pair of bishops 1.♗a6 ♖c6 (1...♖a8 2.♗b7) 2.♗b7.
After 2...♖cd6 3.♗xd6 ♗xd6 (or 3...♖xd6?) White wins the exchange. So far, so good, numerical material gain. However, I'm trying to make my very first baby steps in understanding strategy: In an actual game, assuming I'd see the variation, I'd be hesitating to play it. My -- probably naive -- reasoning would go like this: "A rook is worth five pawns, a bishop three. But White has the bishop pair. Moreover, the rook on c8 doesn't do much, while the dark squared bishop has a nice diagonal. So, I'm not convinced that it's really 5 vs 3."
It's not that I don't trust Polgar/Truong, but I would like to understand. Is it, because after the exchange White is now able to control the d-file? Or am I completely off the track somewhere else?