This is the way i see it, we all know how aquilani is with fitness, so if we have someone like elia then the midfield should be like this elia-marchisio-melo-krasic
and when we want to use aquaman, we go back to using marchisio/pepe on the left,because i would think with elia and krasic,we need 2 central midfielders who are better in defending,and thats why marchi should play instead of aqua