He spent the 2006 season in the San Diego Padres organization, making the Triple-A All-Star team that year, in which he also participated in the home run derby.

Leone was the first Mariner to hit the KOMO Glove sign in left field during a game against the Cleveland Indians to earn a fan $1,000, it was also his first major league home run.

From 2007-2008, Leone played in the San Francisco Giants organization and became a free agent at the end of the 2008 season.

In December 2008, he signed a minor league deal with the New York Yankees and was assigned to Triple-A Scranton.

On September 1, 2009 Leone signed a Minor League contract with the Texas Rangers and was granted free agency on November 9, 2009.