Not that anyone really felt Valencia was the man to fill in at the back in all honesty but the FA Cup game proved it beyond all doubt.
Valencia is not a good defender – yes he can track back as any decent winger has to do in the modern game, but to expect him to actually fill in at the back and bring something to the team other than a one goal deficit is only going to cause problems.
It is harsh to place all the blame on the Ecuadorian himself given Van Gaal is the one choosing to utilise him like this – and that is something that must change in the summer.