The Saints have ruled out quarterback Taysom Hill (concussion), receiver/return specialist Deonte Harris (hamstring), rookie defensive end Payton Turner (calf) and running back Dwayne Washington (neck) for Monday Night Football.
Armstead has not played since Week 3 because of an elbow injury, and McCoy injured his calf only five snaps into the season opener.
Hill was diagnosed with a concussion two weeks ago against the Washington Football Team.
Turner was added to the injury report Friday with his calf injury. He did not practice Friday or Saturday.
Washington and Harris both were injured against the Washington Football Team.