Lulic-Biglia-Parolo is their midfield line. Mauri, who has a great year plays as winger or generally on a free role with Anderson or Candreva on the other side.
Djordjevic is the CF, Klose is benched this season.
I've seen some matches and this year they made very good transfers for Serie A level. They obviously need a CB, since they are all injured or mediocre (except De Vrij) and a CF, because Klose is too old and Djordjevic not consistent.
Lazio can take the third place, since Milan, Fiorentina and Napoli are moderate although they have better squad (bench etc.)