As some one who watched every game we played twice and every team we played during the week leading up to the game you are correct when speaking of 1 player on OL. He was just under sized and didn't have the God given ability. But he had a big heart. Other than that our line had as much God given talent as any, but often didn't play as one and together as a unit like our opponents did. That is not a talent issue.
_____ Poor execution at any position is a mental toughness issue. Like the above post said that comes from discipline. Discipline is instilled during the process of the off season. Nick Saban when talking about his success always talks about the process. The process is not what happens on game day or week. It starts on the first day of your offseason workout.