A person familiar with the deal says the Las Vegas Raiders have agreed on a contract with free agent quarterback Marcus Mariota. The person spoke on condition of anonymity because the deal can’t be signed until the start of the league year on Wednesday. Mariota was the No. 2 overall draft pick by Tennessee in 2015 but lost his job to Ryan Tannehill last season. He gives coach Jon Gruden a proven backup who could also challenge Carr for the starting role.