I think he can play both, Center and Defensive. I also remember Capello playing him couple of games as a winger. He's fast, aggressive, good shooting, stamina, he can play in several positions IMO.
It's true we might not need another DM.... but not too many options we have I think. But like it has been said, letting Tiago go is good for the sake of both sides, and getting a free player eventhough he's a DM isn't a bad thing.