Regarding Chip Kelly & his practices, a recent article said:
"Yet Kelly’s practices are also frenetic because he believes that’s the best way for his players to learn. “When we teach, we implement it in the classroom. We talk about what we are putting in that day,” he explained at a coaching clinic in 2011. “After that, we go to the practice field and do it. The practice field is not where we talk. It is where we do the skills. We want to keep the words there to a minimum. The words you do use must have meaning. [Players] do not want to hear you give a 10-minute clinic in the middle of the field.”
http://grantland.com/features/chip-kelly-philadelphia-eagles-nfl-influence/