If you look at the list of free agent Centers that are still available, look no further than Earl Barron of the New York Knicks. Over the last 7 games of the season the dude averaged 11.7 points and 11 rebounds per game. Yes, I said 11 rebounds per game and he's still a free agent! BTW - a high percentage of those rebounds were offensive.
If he's that good, how come no one knows about him? Well, he didn't play all season except for the last 7 games. Why? He was a D-Leaguer who filled in while Al Harrington, Eddy Curry and Wilson Chandler were all out with injuries. Boy did he respond, the guy played so well he ended up starting and scored 17 points along with 18 rebounds against the vaunted Boston Celtics defense! The "el-stinko" Knicks were 3-4 over those games.
I don't understand why the Knicks haven't signed the guy already. Their loss could be Washington's opportunity. He's probably available for a one year non-guaranteed salary at the veteran minimum. At least bring him in to training camp, and give him a tryout! It's a no-lose situation!