Actually that was very simple. The team was in cap-hell and they couldn't pay these upcoming FA's (Gilmore, Woods, Darby. Brown, Watkins) as they were already against the cap. They did the smart thing of shipping them for draft picks that will be cheap for their first 3-4 years of the contract. That was the only way for them to come out of cap hell. Would the Bill have wanted a shutdown corner like Gilmore or Darby...Absolutely..Did they have the money or cap space to pay them...Absolutely Not!
Dareus was way over-paid and underwhelming. There was no way they would have been able to keep the "Team First" Concept by not paying everyone but an under-achieving player.
Cordy Glenn was the only head scratcher for me. Because we had a starting LT and especially when you lost your interior line to retirement, it would have been prudent to have preserved your starting LT. But that was the only way for them to jump up the draft board to draft their franchise QB.