Gantz was raised in Portland, Oregon, where he was a standout soccer player at the Catlin Gabel School.
While still in high school, he spent one season playing as an amateur with the semi-professional F.C.
In 1993, he spent the collegiate off-season with the expansion Portland Pride of the Continental Indoor Soccer League.
In the spring of 2001, he tried out with the expansion Portland Timbers of the USL First Division but was released on May 25, 2001.
This biographical article related to an American soccer midfielder is a stub.