RB: You can sign Rafinha (good first team member) or Ansaldi (not too good for first team but good prospect). But isn't Srna good enough? He's better than both of them.
CB: Mertesacker, Naldo, Zapata. Why do you want CB though? Lescott and Kolo Touré is enough.
LB: Vargas, Filipe, Criscito