If you look at all the strikers that/are played[ing] under Benitez, or that he's favoured. Crouch,Morientes,Carew and Mista. What do they all have in common? All four of them can hold up the ball, get the rest of the team into the game.
Does Cisse have that ability? No. His only attribute is speed. He has nothing else. Poor first touch, poor ball control, poor dribbiling, poor decision making and poor passing.
When he shoots on goal, nine times out of ten he goes for power rather than accuracy.