user11904: 
e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6 6. Bc4 e6

1) For 6. Bc4 Black can play immediately b5 and attack it. But almost all Grandmasters reply with 6....e6. Theory also stresses to 6....e6. Why not 6.... b5 to attack Bishop immediately as 5....a6 is already done? Is it not giving Black a strong attack against White? Hence, why Grandmasters are not playing early 6....b5 in their games? Expecting good answer. Thanks in advance.  

user12873: 6...b5 7.Bd5! Nxd5 8.exd5 leaves Black in trouble. The e-file has been opened and Black has to figure out how to castle before things get really heated. The c6-square is also a major weakness that White's d4-knight is ready to jump to at the right moment.

11904: <ol>
<li>e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6 6. Bc4 e6</li>
</ol>

<p>1) For 6. Bc4 Black can play immediately b5 and attack it. But almost all Grandmasters reply with 6....e6. Theory also stresses to 6....e6. Why not 6.... b5 to attack Bishop immediately as 5....a6 is already done? Is it not giving Black a strong attack against White? Hence, why Grandmasters are not playing early 6....b5 in their games? Expecting good answer. Thanks in advance.  </p>
 12873: <p>6...b5 7.Bd5! Nxd5 8.exd5 leaves Black in trouble. The e-file has been opened and Black has to figure out how to castle before things get really heated. The c6-square is also a major weakness that White's d4-knight is ready to jump to at the right moment.</p>
