Well you can't just say "He deserved it more than some of our other mistakes, so we should have signed him"
Those other mistake signings are the signings that prohibited us from signing Papelbon. I'd absolutely rather have Lackey than Papelbon, but we have Lackey, so they couldn't spend the money on Papelbon.
By no means am I defending some of the signings that this team has made, but at the same time you have to realize that the mistake signings are the signings that prohibited the Papelbon signing.