Candice Ward/Getty Images Ashton Jeanty of the Las Vegas Raiders runs at rookie minicamp in Henderson, Nevada. Ashton Jeanty was one of the greatest running backs in college-football history. But he’s already adjusting his game to win favor with his Las Vegas Raiders coaching staff. Jeanty has adopted a new pre-snap stance at the suggestion of Raiders’ first-year offensive coordinator Chip Kelly, who used a unique way of selling the Boise State rookie. “Chip Kelly comes to me, first day of