I don't think Hansen is part of the FO's plans this fall as much as Papelbon. Tito said after his start against Minnesota that he and Theo talked earlier in the year about Papelbon going into the pen. The guy was an effective closer in college and while he's young he at least is mentally suited to come in and get outs. Back in '86 the Sox rushed up Calvin Schraldi out of Texas and he fell apart in the playoffs and was never the same again.
Foulke is the key, and if not, cross your fingers with Papelbon.