throw, their ability to run is usually effective for on a limited amount of time. RGIII couldn't figure out the throwing. Kaepernick couldn't throw. Vick had decent success but nothing like his early years. Even going back, Randall Cunningham's best year was when he was throwing it for the Vikings. Steve Young became more of a passer than runner. While Jeff Hofstetler couldn't maintain his Giants success because he couldn't throw.
The bottom line is the QB position is a throwing position. If you can't throw, your running ability will only be successful for a season or two. Maybe three, but after that, you better have learned how to throw or you'll quickly find your game limited.