Seriously... The more Tommy Rees keeps calling those slowly developing draw plays out of the shotgun on 4th and 1, the more it makes me convinced that he's scared to death to defy the Brian Kelly school of thought.
A straight run from under center, as you well stated, is going to get you that yard or two, especially with a powerful runner the likes of Estime. A QB sneak will almost always get you that one yard you need. I honestly don't know why Rees is so afraid to call either play except for the above.