I was playing through the game Smyslov-Nunn 1982 (see full game here: http://www.chessgames.com/perl/chessgame?gid=1103145
) and came across the diagrammed position below.
Here Smyslov played 8.Bb5, and the game continued 8...Bd7 9.0-0 a6 10.Bc4.
Could someone help me understand why Smyslov played the bishop to b5? Perhaps he wanted to capture the knight to inhibit an e5 advance (I don't know if I like that idea), but black can play Bd7 (as he did in the game), which looks like a natural enough square for that bishop anyway. After 9...a6, Smyslov has to move the bishop back to c4 but it seems like black has been given a free tempo to play a6. Why not just put the bishop on c4 initially with 8.Bc4?
Forgive me if this is a dumb question.