He isn't developing. He isn't getting better. He's regressing. It's obvious that he has no idea how to approach and prep for an NFL game. Cam Newton was a more refined passer than RG3. He also had a playbook at Auburn.
As an SEC fan and an Arkansas fan....

The Auburn offense is not an NFL type offense. Gus Malzahn's strategy is get the biggest, fastest guy the ball and get out of his way. It works when you have players, but don't confuse success with complexity.
Also, lack of a hard copy playbook does not mean Baylor runs a free for all "run deep" offense. It means the coaches know many players don't look at it enough and instead drill down on repetition, film, and on field work. The high school I was at had a pro style offense with numerous motions, different protections, personnel packages, formation shifts, and all the jazz, but no playbook was ever used. No doubt in my mind a college coach with more time could install an offense without a playbook. Baylor proves that. RGIII is smart enough to understand a playbook. Certainly a heck of a lot smarter than Cam Newton.
Here is Cam Newton breaking down that big Auburn playbook;