Viera started with the Trenton Thunder, the Double-A affiliate of the Red Sox, in the 2002 season. He was promoted midseason to the Triple-A Pawtucket Red Sox. His season began strong but his performance dipped towards the end, which he and the Red Sox international scouting coordinator attributed to his need to adjust to the more intensive American training schedule, particularly since Viera had missed a year playing. Due to his disappointing performance, the Red Sox released Viera from his contract after 2002, giving him the free agent status he wanted in the first place. Viera then played for the unaffiliated Newark Bears in the 2003 and 2004 seasons.