By Katie Catherall Manchester United manager Erik ten Hag refused to dig out Casemiro for his costly error in Sunday’s 1-0 loss to Arsenal, but stressed that not having a consistent backline has cost his side all season. Pressure is mounting on both Ten Hag and his Red Devils squad after recording yet another loss, leaving them on the verge of missing out on a place in Europe. Their defeat to Arsenal came less than a week after a 4-0 thrashing at the hands of Crystal Palace. Ten Hag has been forced to deal with regular injuries and yet again had to deploy a makeshift squad for the visit of Ars…