Current closers the Red Sox had a the possibility of acquiring after Papelbon departed:
Joe Nathan
Rafael Betancourt
Rafael Soriano
Casey Janssen
Andrew Bailey
Joel Hanrahan
Among those, they chose the fat one and the injury-prone one. There are some others that probably escape me, but Jesus, the Papelbon whining is reaching critical mass.
The contract is still stupid, and they could have replaced him adequately, but didn't.
There's also the fact that, by all accounts, Papelbon did not want to come back after the 2011 debacle. He didn't even give the Red Sox a chance to make an offer.
That's one thing that fans refuse to accept. Players are human beings, not robots, and they get to choose where they will play.