Essien can still be used a defensive mid when Mikel or someone else isn't available. When you look at the players coming in or coming back, such as DeBruyne, Benayoun, Marin and Kakuta, they're all attacking mids/wingers. McEachran is the only 'new' option in central midfield. As far as Kalou goes,..he hasn't been released officially. If I'm correct, the club will leave Kalou's contract extension in the hands of the new manager.