 Estrada spent the 2006 season with the Rookie-level Gulf Coast League Nationals, and the Savannah Sand Gnats of the Class-A South Atlantic League.He posted a record of 3 wins and 4 losses and a 3.98 ERA over 61 innings, consisting of 12 starts and 1 appearance in relief, striking out a total of 56 batters and walking 20.In 2007, Estrada pitched for the GCL Nationals, the Class-A Hagerstown Suns of the South Atlantic League, and the Advanced-A Potomac Nationals of the Carolina League.