I know this won't be popular, but I think Dietmar Hamann has to do a bit more.
When the centre backs win those defensive headers it is up to Hamann to pick up the lose ball most of the time, but he hardly does so, also some times he needs to push foward beyond the half way line and control the play in the oppsition half, he is probarly the only player with the technical abilty to do this. I know that the the fact he lacks pace limits this, but sometime he has to take risks.
He's doing well but he can do better.