SEATTLE—When called upon three weeks ago, Colt McCoy viewed himself as a caretaker. The Arizona Cardinals were already off to a terrific start. McCoy’s job when Kyler Murray went to the sideline with an ankle injury was to avoid giving away what the Cardinals already accomplished. McCoy more than did his part, and his best performance was likely his last start for Arizona. With Murray out one more week, McCoy threw for 328 yards and two touchdowns, and the Cardinals beat the Seattle Seahawks 23–13 on Sunday. McCoy went 2–1 with Murray sidelined, including divisional road wins at San Francisco and Seattle. The Cardinals will go into their bye with the best record in the NFL and the expectation of Murray and DeAndre Hopkins returning after the break. “It’s just my responsibility. That’s how I see it,” McCoy said. “I came here to be a part of this team and …