MIAMI GARDENS — I don’t know how the Miami Dolphins got into this troubling situation with their backup quarterback, Skylar Thompson, who was benched after two plays in Sunday’s 34-15 win over the New England Patriots. But it raises a bigger question: Who is in charge of the Dolphins’ 53-man roster, Chris Grier, the general manager, or Mike McDaniel, the coach? “I think by the letter of the law, Chris Grier is the man,” McDaniel said Monday.