Daniel Murphy or Alberto Callaspo?

Looking to add a MI off the waiver wire to fill in for the slumping Kelly Johnson.

Who would you select between Daniel Murphy and Alberto Callaspo?

Murphy seems to be looked into the #2 spot in the lineup between Reyes and Wright.  Callaspo hit in an RBI spot at 6th in the batting order.  Both have playing time issues, so I think that's a wash.  They both actually seem like similar high contact hitters who don't strike out much.  Murphy is technically in a platoon with Justin Turner, but the way Murphy has been hitting lately, I think his days on the bench will be less and less.  Callaspo has been hitting all season long, however, with Erick Aybar and Macier Izturis both in the picture, I could see Aybar at SS and Izturis at 3B a couple of times a week at least, leaving Callasop on the bench (although he should be playing everyday imo).  I know its not a major move, but I've got an empty roster spot, so just looking to add a guy to play in the short-term while Kelly Johnson continues to struggle.  For what its worth, its a standard 5x5 roto league.