You can't play a successful 433 unless you have 2 outstandingly good passers of the 3 mids. Diego cannot play wide-forward. he has played deep in midfield before though, did it for Brasil many times when he was in their lineup and
is stronger and tougher in the tackle than Iniesta will ever be. My 433 would look like this
Gio-------------Trez------------Camo (or Ribery

)
---Marchisio----------------Diego-------
----------------Sissoko-------------------
....