 Polo posted a combined .301 batting average with five home runs, 44 RBIs, 34 stolen bases, and an .805 OPS in 95 total games between Tampa, Trenton, and Birmingham.Polo played the entire 2018 season with Birmingham and elected free agency on November 2, 2018.On November 28, 2018, Polo signed a minor league deal with the Seattle Mariners.