Yeah should work on it, not only his positioning there are few aspects where he should improve a lot to play for a team competing on all fronts.
CM/DM can sit back and help fullback. Will agree to disagree though. With Essien maybe they would have controlled the game, who knows.
Zonal marking explains what i mean better about Ivanovic. Essien would also have been my choice, but it is not the key problem there.