Background and college
Born January 7, 1980 in Llano, Texas, Kassell attended Llano High School and was a letterman in football as a quarterback. In football, as a senior, he rushed for 1431 yards and 20 touchdowns and passed for 839 yards and eight touchdowns, and was named the Class 3A All-West MVP, and won All-State second team honors. Kassell was a four-year letterman who played in 44 games at the University of North Texas and was named Sun Belt Conference Defensive Player of the Year during his junior and senior season. He received a unanimous first-team selection to the conference teams and was team MVP in his final two seasons and ranks third on the school's all-time tackle list. Kassell majored in business administration.
Before the Jets
In 2002, he was signed as an undrafted free agent by the Tennessee Titans. He played for the team from 2002 to 2005. In 2004, Kassell set a career high with 19 tackles against Detroit, and tied for most in franchise history.
As a Jet
In 2006, Kassell was signed as a free agent by the Jets. In his first game as a Jet, against his former team, Kassell was named Jets special teams player of the week after recording three tackles in kick coverage in season-opening win over the Titans. In 2007, Kassell was selected by teammates as special teams captain along with Mike Nugent and led the Jets special teams with 26 tackles.
Kassell is married to Marcy, and has two daughters, Saydie and Madison.