There were shades of that Southampton display in the way Manchester United dispatched Barnsley in the Carabao Cup. At St Mary’s on Saturday lunchtime, Erik ten Hag’s team started sluggishly. They struggled to wrestle control of proceedings and needed an Andre Onana penalty save to spark them into life late in the first-half. If Onana provided the turning point on against Southampton, then it was Marcus Rashford who did the honours as Barnsley came to town. Darrell Clarke’s third-tier visitors settled well, even flashing a few dangerous crosses across Altay Bayindir’s goal. But once Rashford ro…