Gillen is a mid-year transfer from Florida Gulf Coast University.
At Estero High School, Gillen was a four-year letterman and starter. He accumulated an ERA of 2.47 during his high school career. Gillen was ranked as one of the top-500 national prospects, accoriding to Perfect Game. Gillen also participated in a veriety of showcases including: the 2016 East Coast Pro Showcase and the 2016 Florida Diamond Club.
Nate is pursuing an associate's degree in Finance at SCF.