The problem is that for decades, Mexico City has been using oil revenue as a way to fund the federal government, and they haven’t been pouring back any real amount of the profits into modernizing equipment, R&D, ect. Pemex hasn’t been investing for the long term, and they’re beginning to pay the price. The federal government of Mexico gets close to 40% of revenue from Pemex. If you think things are bad down there now...
Venezuela under Chavez has the same sorts of problems as well. Which is another reason to build Keystone, in order to ensure raw material for the Gulf refineries currently refining Venezuelan oil.