I don't like that idea at all. One of the Eagles 3-4 major focuses should be adding depth to their O-line, and getting rid of starters doesn't help that.
I wonder who the Eagles would be after at that spot though. I think they should drafta WR 1st round, if not at lest 2nd, but I would think someone like Michael Jenkins or Lee Evans (likely to be around in late 1st round) would do fine. Stephen Jackson crossed my mind, but Westbrook is already a talented back, albeit unproven as a feature runner.
The only real advantage I can think of would be to pressure another team into trading a 2nd round pick to move up into where the eagle are, so they can select Jackson. However, that'd essentially come out to gaining a mid-late 2nd rounder for a starting Guard... ?!?