Nelson attended Fairmont Public School where he received All-State honors in football.
He became a starter for the Cornhuskers at the stand-up defensive end position as a sophomore, registering 42 tackles (20 solo), 3 fumble recoveries, one interception and one blocked punt.
Nelson was selected by the Dallas Cowboys in the fourth round (108th overall) of the 1981 NFL draft, with the intention of playing him at linebacker.
In 1982, he signed as a free agent with the San Diego Chargers, but suffered an injury during preseason and was placed on the injured reserve list on August 30.
[5] His uncle Bob Cerv was a Major League Baseball All-Star with the Kansas City Athletics and the New York Yankees.