49ers key to success: DE Justin Smith

Justin Smith was a prototype 4-3 defensive end when he came to the 49ers in 2008, having played the position throughout his football life. Now he’s one of the most respected, productive and feared 3-4 ends in the NFL. Smith just keeps getting better as he enters a new season as the undisputed leader of the Niners’ defensive line, a unit in transition that will be counting on him to show the way.