He always moved poorly. That's why Davydenko keeps beating him on every occasion.
I know it must be tough for a tall guy he is, but unless he improves it there is no way he could climb the ranks and be a solid top 10 or even top 5 player.
In women's tennis it's possible to outhit other players even if your movement sucks, but on ATP that's practically impossible. This is the area where Berdych needs to work the most.