Rumor on local sports radio was that Gannon would be cut after the Chargers signed Rivers. The idea being that they didn't want Gannon going to San Diego. (Please don't make me spell out the details of this convoluted logic.)
Any rumor heard on sports radio has to be taken with a huge boulder of salt. Rivers has signed, and Gannon still seems to be slotted to start for OAK. Gannon will have to play himself out of the starting role.