López signed with the New York Yankees in 2002. He played in their minor league system until he was released in 2007. He signed with the San Diego Padres two days later.
In 2007, López played for the Fort Wayne Wizards and Lake Elsinore Storm, going 1–0 with a 3.30 ERA in 22 games for the former and 2–1 with a 6.10 ERA in 22 games for the latter. He played for the Storm, San Antonio Missions and Portland Beavers in 2008, going 2–1 with a 2.64 ERA in 30 games with the Storm, 0–2 with a 4.93 ERA in 27 games with the Missions, and 0–0 with a 9.00 ERA in one game with the Beavers.