RGIII is too short to be a classic pocket passer. Just look at the guy when he stands next to Luck. RG3 is listed at 6-2 and looks 6-1 to me. Plus, he releases the ball at about ear level. His release point is too low, and that means his passes will have a bigger arc than the taller passers. Bigger arc means more time for the defense to attack the ball.
Play it smart and he can have a career like Fran Tarkington.