Headley is 4th among all 3Bs in defensive value since 2010. That decent OBP would rank 2nd on our team, and his power is really kind of a question mark (though I'd think it would play well in GABP on a regular basis).
It would also allow us to move Frazier, who is a better bat than Ludwick or Heisey at this point IMO, to left field.
But as mentioned I didn't really think it through in terms of his contract.