ジャクソン・ジェネラルズ
Siverio signed a minor league contract with the Seattle Mariners organization on November 17, 2014. He pitched for the Jackson Generals of the Class AA Southern League in 2015, recording a 5-12 record and 4.35 ERA with 110 strikeouts in 26 appearances. On April 1, 2016, Siverio was released by the Mariners organization.