Why do the Redskins throw away Draft Picks??

How come it seems like EVERY YEAR the skins trade away their draft picks during free agency. has anyone else noticed this? They constantly pick up older players who were good with one team and then do nothing when they get here. The Skins are currently trying to give the Bears their #6 overall pick for Briggs... but if they do that they have NO other picks in the first 4 rounds. It is ridiculous. I mean sean taylor was our last good pick.