Manchester United have had quite a few sobering days at Old Trafford since Sir Alex Ferguson retired so there’s an air of expectancy now, as sad as that is. Still, the way Arne Slot’s Liverpool, in only his third competitive game, ran circles around Erik ten Hag’s side was an inexcusable sight. United started in a fairly competitive fashion before it was the Casemiro show, for all the wrong reasons. He gave away the ball for the two first-half goals which put Liverpool in the driving seat, a position they never relinquished. Even apart from the two mistakes directly leading to goals, he looked…