Will the Raiders stick with Derek Carr, or is Mariotta a ploy to trade or cut Carr?

They will go with Carr and only replace him if he gets hurt. 

DC. all year. Any changes would only happen as a result of injury but our OLine will protect him!!

Depends because if we start off hot then carr will remain the starter But if not and we go 2-4 then we will forsure hand over the job to mariota to see what he can do with our offense. Lets  just see what happens, but for us to make playoffs carr will need to not play scared and instead of throwing the ball away he needs to actually go out and make the play if he doesnt see anything he likes, run and be mobile because thats where the league is heading towards is all these mobile fast quarterbacks