What we're seeing is most likely the result of a QB who's mechanics in his college scheme don't translate to his NFL scheme and he's struggling to put the footwork and throwing process combined with the processing of information together in such a way that the ball comes out naturally for him like it did at Cal.
Keep saying this, but the problem with attempting to take an Air Raid style developed QB in college and turn him into a pro style QB in the NFL is that he effectively has to learn how to play a new position. And we know very few, if any, have succeeded to a high degree at accomplishing that. If it is to happen, it could take a long time to unlearn everything he learned, most likely since high school, and learn how to do it at a high level in a pro style offense.
He's just extremely uncomfortable right now and it shows, at least to anybody willing to watch objectively. Part of the discomfort is manifested in the number of ugly balls he's throwing. He threw a pretty ball at Cal.