Why Rimando With Adu?

Seeing that Real Salt Lake has now traded Nick Rimando to NYRB for future considerations, I found myself wondering why they took him in the trade in the first place. It would seem that Ellinger wasn't interested in keeping him around to compete with the less than convincing Scott Garlick. Why take Rimando in the trade in the first place? One would think that DC would be looking for more than just a major allocation for Adu. After all, he is the single most promising American prospect in the game today. Why didn't RSL work to at least get a decent developmental player out of it? RSL does still have some needs to be addressed for 2007 such as strengthening their backline, finding a good backup for Garlick, and some bite for their midfield. Instead they end up losing a major allocation and bring in Adu for a position they were already strong at with both Andy Williams and Medhi Ballouchy more than capable of playing an attacking role in the middle of the park. Did this happen simply because DC United didn't want to be the ones trading Rimando away to a rival team?