One of Allen's most memorable plays occurred October 3, 1993, in a game against the New York Jets. Having lost their starting quarterback (Randall Cunningham) to a fractured fibula early in the contest, the Eagles found themselves trailing the Jets by two points late in the 4th quarter as the Jets drove downfield for what would likely be the game's final points. Jets quarterback Boomer Esiason attempted to throw for a first down inside the Eagles 10-yard line as Allen stepped in front of the intended receiver at the 6-yard line.[5] The ensuing 94-yard touchdown return was declared "Greatest Interception Return in NFL History" by Steve Sabol of NFL Films.
After several successful and injury-free seasons at Philadelphia and New Orleans, Allen blew out his knee during the 1998 season on November 15 while playing for the Oakland Raiders against the Seattle Seahawks and missed the rest of that season. But he came back strong in 2000 and had a season to remember, with six interceptions, including a team-record three for touchdowns. His teammates honored him with the first annual Eric Turner award for the Raiders' most outstanding defensive player. The award was created in the memory of the Oakland free safety who died of abdominal cancer in May 2000.
Through the 2001 season, Allen played in 216 of a possible 224 games.
Allen joined ESPN in August 2002 as an NFL studio analyst. Allen primarily appears on ESPN's "Sportscenter" as an NFL analyst.
Allen has had appearances as a college football analyst on the Pac-12 Networks football shows, as well as for the station's flagship show "Sports Report" as a football analyst.