Some where surprised when it was revealed that the Eagles had signed Demetress Bell to a 5 year deal. Soon after it made more sense when it was reported that only the first year had guaranteed money. So what's the strategy here?
I can see two main reasons. One, the Eagles have hedged themselves against Jason Peters' injury being worse than expected. Typically an Achilles rupture is a 9-12 month injury. So, by the start of 2013 he'll have had a year and a half and should be ready to go. Still, it is also an unpredictable injury, so if Peters is not ready to go Bell will still be here and signed.
But if we look at the best case scenario, which is that Jason Peters comes back healthy next season, then what to do with Bell? The interesting thing about this deal is that if he starts and plays even league average level LT next season, he'll become a very valuable trade chip in 2013. 28 year old, starting caliber LTs are not plentiful in this league, it stands to reason that he would be in demand (again, should he stay healthy and play well.) The best part is, since the last four years of the deal have no guarantees, he can be traded with no cap penalty.
Of course, the worst case scenario is that Bell can't stay healthy and/or struggles... but at least the Eagles can just cut him after this year. It's really one of those deals without much downside for the team.