Cassel went 26-of-35 through the air with two TDs and an interception.
His favorite target was Greg Jennings, who made 11 grabs for 163 yards and a touchdown.
Nick Foles amassed 428 passing yards with three scoring strikes on 30-of-48 efficiency, but it wasn't enough as Philadelphia (8-6) had its five-game winning streak snapped.
The Eagles came into the day with a 1/2-game lead over Dallas in the NFC East.
DeSean Jackson made 10 catches for 195 yards and a touchdown.