IMO, despite their loss to Honduras last week, El Salvador is either the best or 2nd best team in this tournament so far, and we played them pretty okay (not perfect by far) in that first game.
I think even in our flawed but improved form, we can take on Mexico and possibly pull off the upset. I know we still have far to go, and yes it is a building process, but some of the fundamental intrinsic aspects of the game should at least still be evident in our approach in the Mexico game.