It's not immaturity at the point where he's a malcontent or he's going to get himself into trouble. It's immaturity where he can be one to take something very lightly when it should be taken seriously. Such as practice, or eating right, or being diligent in staying in shape. He's still a college kid, i guess.
If Carson Palmer = Troy Aikman, then I'd say....
Jordan Palmer = Danny White. The talent is there, just needs a few years to grow into the position as a back up.
Jason Garrett spit in the parking lot this morning...
That spit knows more about football than any of us.