Jimmy Walker secures his 15th title this season with a four-shot win . Walker held off a late challenge from runner-up Jordan Spieth . 21-year-old Spieth carded four birdies on the last five holes .
Jimmy Walker secures his second title this season with a four-shot win . Walker held off a late challenge from runner-up Jordan Spieth . 21-year-old Spieth carded four birdies on the last five holes .