The middle child of three boys, Cassidy was a student of St. Agnes elementary for one year before joining his brother at St. Anne's Elementary School in the Sunset District.  After graduation, Cassidy went to a rival high school of Ramsey's, Saint Ignatius College Preparatory in San Francisco. Led by the Jesuits of SF, Cassidy, like Ramsey, was a multi-sport athlete as member of the Wildcats' athletic program.  Cassidy competed in Basketball, Baseball, Golf, and Football.

   As a senior, he helped lead his basketball team to a victory against No. 1 seed, Balboa High School, in the NorCal quarterfinals. In the game, Cassidy scored 35 points and made 9 consecutive three-pointers in their overtime win.  Watch the game here.

    Cassidy then went to the University of California, Berkeley where he walked-on to the Berkeley Men's Basketball team as a freshman.  Cassidy joined fellow SI alums Justin Labaugh and JT Stephens as a part of a Sweet 16 appearance in the 1997 NCAA Tournament. He played for four years with the Bears before working as a Sports Information Director after graduation. After a year, he was back on the sidelines with the basketball team, working as the Video Coordinator and Graduate Assistant coach.

    During his two years as a member of the Cal staff, Cassidy earned a Master's degree in Sport Management from USF.  He then accepted a job in Los Angeles as an Athletic Academic Advisor at USC.  After three years with USC and two football national championships Cassidy returned to the Bay Area and take job with his alma mater, Cal as an Academic Advisor.