Jimmy Spieth secures his second title this season with a four-shot win . Spieth held off a late challenge from runner-up Jordan Walker . 21-year-old Walker 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 .