I mean I believe there is truth to the Eagles trying to get an extension worked out. If they can't find a way to get Mariota then Bradford is their man.
However, the timing is awfully peculiar. There's not shot in hell that the Eagles would agree to a contract with Bradford BEFORE the draft. Say Mariota falls to 20 but now the Eagles just signed Bradford so they're stuck with him. It could be one of many camps that are trying to put rumors out there.
It's not like Bradford is in a position to lock down a huge long term contract though, his contract would likely not have a ton of money guaranteed beyond this season. They could sign him, and if Mariota falls you have an expensive backup for him when he's ready to start.