Cassidy was assigned to the
New Orleans VooDoo of the AFL on February 16, 2011. He was reassigned by the VooDoo on April 18, 2011. Cassidy appeared in two games for the
Columbus Lions of the PIFL in 2012, throwing one interception on two incomplete passes. Cassidy was assigned to the
Pittsburgh Power of the AFL on April 4, 2012. On April 14, 2012, the Power overcame a 48–17 deficit to defeat the
Orlando Predators by a score of 57–54 in overtime, setting a new record for largest comeback in AFL history. Cassidy, who entered the game in the second quarter after an injury to
Andrico Hines, completed the game-winning touchdown pass to
Christian Wise. He completed 48 of 79 passes for 566 yards and 12 touchdowns with six interceptions in 2012. He played in six games for the Power in 2013, recording seven touchdowns and four interceptions. ==References==