Our players don't play with such an intensity. Shaw I don't believe has the stamina to play like that and that's what is required in the modern game for a fullback. Even last season when we all praised Shaw, it was in Solskjaer's low/mid block as a fullback and not in the uber aggressive front foot approaches we see the likes of Klopp, Guardiola and even Potter implement.Just watch Cucurella today and compare with Shaw. You will see what are we missing .
The role of the fullback is to help in attack first and then to support defensively, because if the aim is to create a system to impose a style on the opposition, then the fullback has to be seen as a attacker first and defender second.