Don't be ridiculous sir, I did not just say that... Spain play the double-pivot with Sergio Biscuits and Xabi Alonso (and would thus be familiar with it), not saying it would be a standard deployment of our team, but a possible alternative. I don't see how you could have possibly misconstrued my words any more, at least you could attempt to do so with a smattering of good humour.
Why would it be weak defensively, Xabi Alonso is essentially a hybrid defensive midfielder and a playmaker who can perform both functions, whilst Pirlo is more a pure deep lying playmaker; then Vidal as we know, is an all out, tireless and defensively apt box-to-box midfielder who can competently support the team both in attack and defence. Your statement (or poor excuse of an argument) is thus both baseless and invalid.