After 1. e4 c5 2. Nf3 Nc6 3. d4 cxd4 4. Nxd4 e5 why is 5. Nb5 the best move? The game usually continues 5. Nb5 d6 6. N1c3 a6 7. Na3 and it looks to me like whites knight on a3 is misplaced. What makes this line good for white?
[StartPly "8"] [FEN ""] 1.e4 c5 2.Nf3 Nc6 3.d4 cxd4 4.Nxd4 e5 5.Nb5 d6 6.N1c3 a6 7.Na3