Semi-rosterbation but with only one move in mind. The Mets management are not the ones that signed Bay, and after a year he has obviously not panned out -- though he may in the futre. Bay is worth 16 mil per year until 2013 and Uggla is 13 mil per year until 2015. Bay also has an option at 17m with a 3m buyout.
Over the careers of both, Bay has been the better performer. It's quite possible that the Mets would be the team to turn down this trade, and I would put every cent I had on it never happening regardless, but it is an interesting idea to think about. It's far too early to think that Uggla will be a below average player for the remainder of his contract, but guys like him do age quickly. Food for thought.