Hermansen played amateur ball as a shortstop at Green Valley High School of Henderson, Nevada, and the Pittsburgh Pirates selected him in the first round of the June draft, with the tenth overall pick.

He earned a promotion to the major leagues at the end of that season, and made his debut against the San Diego Padres on September 7, 1999.

Hermansen was viewed as the Pirates' center fielder of the future, but he struggled to establish himself and lost his starting job early in 2000.

He spent parts of the next three seasons bouncing back and forth between the Pirates and Triple-A, and then was traded to the Chicago Cubs for Darren Lewis on July 31, 2002.

Lewis chose to retire rather than report to the Pirates, so the teams made a follow-up trade involving minor league players Aron Weston, Ricardo Palma, and Tim Lavery two weeks later.