Early on in the match, it's become pretty obvious that El Salvador has two goals against Mexico: Pack the midfield and deny service of the ball into the feet of Andres Guardado. To combat the latter problem, Mexico is swapping Guardado and Pablo Barrera between the left and right sides, but it hasn't done any good so far. Guardado isn't being allowed to have an impact on the game, and it's stifling El Tri quite a bit. El Salvador did their homework.
Still, Mexico have much more of the possession and they've created a couple of half chances. It seems like a goal is on the way for them eventually, but it's not going to come easy. El Salvador's defense has been great so far and it might be tough to crack.
There's no reason for Chepo de la Torre to do anything dramatic, even if things aren't going exactly to plan so far. This is his best setup and his best personnel group, and they have a better chance of figuring this out than any other players do.
For more information on the Mexico Vs. El Salvador game, the 2011 Gold Cup (Copa Oro), and Mexican football in general, check out SB Nation's Mexican football blog FMF State Of Mind.