Again, intangibles like "heart" DO matter. Maybe you want to call it something different - mental toughness maybe.
Aaron Rodgers won a Super Bowl with a subpar running game, others have done it. The difference is that he can take a sack or throw a pick and go to the sideline and start looking at photos and planning the next drive. Guys like Cutler spend too much time yelling at linemen or offensive coordinators.