So are you thinking Isco and Navas will be playing more centrally? If we really are going for the 4-3-3 model then I can see their being 2 distinct ways to go about it. Play with two forward wide men able to either beat the man, cross it to the central striker or play it centrally toward a three man midfield of Fernandinho/Rodwell , Yaya and Barry/Milner/Garcia. Alternatively, we play with 2 or even 3 'strikers' up front so Tevez, Dzeko and Aguero or perhaps, 2 'strikers' and a wider player such as Silva/Isco/Navas and then have 2 holding players and an advanced playmaker type in Silva or Nasri, perhaps even Yaya, however I think he is more effective moving forward late in the game as it creates another dimension of attack and forces the opposition to adapt and change. The second option would be perhaps more fitting and adaptive to all players that we have.