I see your point and agree that the system QB is a valid concern, but most of those QBs were athletes who couldn't throw the ball that well but could run the option portion of the offense and learned to throw on the fly. Mariota has been a very productive QB his entire career. He's much more of a passer than guys like Dixon, Tebow, etc. Yeah I look at Mariota as a bigger and stronger Colt McCoy.