There had never been an Eagles season like the last one, which means, in turn, that there has never been an Eagles season like this one. So it's difficult to find a historical corollary that can account for their regression from the franchise's first Super Bowl-winning club to a team that has lost four of its first seven games, burping up two double-digit second-half leads along the way.
When you've never won a Super Bowl before, you've also never had to be a defending Super Bowl champion before. Again, this is unprecedented stuff for the Eagles, and this season really is uncharted ocean.