Nelo was drafted out of St. Thomas University in the 17th round by the Texas Rangers in the 2007 draft. He also played for Savannah State University.

 His best season came during his bid with the Nationals, in 2011 with Potomac of A+ ball. He sported a 2.40 ERA in 36 appearances, he struck out 63 batters in 52.2 innings pitched while only walking 29. His WHIP was also a career best 1.161.

Last season was his first full out of affiliated ball, and he played with the Jackals. With New Jersey, he was impressive, with a 2.00 ERA in 35 appearances, 21 saves, and 45 strikeouts compared to only 19 walks in 36 innings pitched.