Five years ago, drug violence was exploding, the economy was reeling, and a Pentagon report likened Mexico to the terrorist-infested basket case Pakistan, saying both were at risk of “rapid and sudden collapse.”Now the alarms about Mexico are being replaced with applause. After one year in office, President Enrique Peña Nieto, 47, has passed the most ambitious package of social, political and economic reforms in memory. Global economic forces, too, have shifted in his country’s direction. Throw in the opening of Mexico’s oil reserves to foreign investment for the first time in 75 years, and smart money has begun...