Tarrasch Defence

Hi,

I am currently reading Eric Schiller's book Encyclopedia of chess wisdom, and there is a special opening of the Tarrasch Defence that I don't get. It goes as follows:

1.g3 d5; 2. Nf3 c5; 3. Bg2 Nc6; 4.d4 e6; 5.0-0 Nf6; 6.c4 Be7; 7.cxd5 exd5; 8.Nc3 0-0.

Why wouldn't black simply play : 4.d4 cxd4 Nxd4 5.e5

Thank you for your help, I am new to chess and there is probably something that I don't get but from my beginner's eye exchanging the c pawn for d pawn is an advantage for black.

Methinks you mean 4...cxd4 5.Nxd4 e5 which is entirely possible.  I am no expert on this opening, but next White could play 6.Nxc6 bxc6 7.c4 and now the d-pawn becomes a target.  Kind of a role reversal, where White has allowed (indeed assisted!) black in setting up a classical pawn center, only in order to take shots at it from the wings.

In researching the position after 5...e5 I came across 79 games with a score of 72% for White (+63-15=14).  Maybe there will be a Tarrasch expert respond.

Eric_C is correct, White is playing the Grunfeld with an extra move. Who wouldn't want to play this for White? Also from Black's point of view, why would Black transpose to this when he purposely started out playing a Tarrasch?