We are looking at best-case scenarios for mid-round draft picks of the San Francisco 49ers.Player: Marcus MartinPosition: CRound: 3Earliest he could have big role: Week 1.Why is there an opportunity? Jonathan Goodwin, who started the past three years, was not brought back in free agency.Who is in his way? Daniel Kilgore. The 49ers like him. They gave him an extension this offseason and think he is capable of starting.Current thoughts: The edge goes to Kilgore.