SacramentoBob
Footballguy
It's a move that maintains some imbalance in the position.
If Nxc3, that preserves the IQP position and trades off a set of minor pieces, but at the cost of aiding his development slightly.
If bxc3, that switches to a hanging pawn structure for White.
If we just retreat to d6 and he captures on d5, we have a pretty boring symmetric position with very little risk. I doubt he captures on d5 though. Bd6 is fine.
If Nxc3, that preserves the IQP position and trades off a set of minor pieces, but at the cost of aiding his development slightly.
If bxc3, that switches to a hanging pawn structure for White.
If we just retreat to d6 and he captures on d5, we have a pretty boring symmetric position with very little risk. I doubt he captures on d5 though. Bd6 is fine.