Justifying this contract, by saying Arroyo is durable is silly. Considering Arroyo's age, it's like saying "I don't worry about my 90 year old grandpa driving, he's never been in an accident!" Arroyo may never spend time on the DL, but with his declining skillset, he is a liability to the team, just like the 90 year old driver with poor coordination is to everyone on the road.
Seeing that the pitchers just below Arroyo are going to be signing minor league deals (Capuano, Maholm, Saunders, Baker, etc.) This deal makes no sense at all. If I was the Orioles, or Diamondbacks for that matter. I would have sat out free agency this year, and waited for my pitching prospects to develop, and a better crop of free agent starting pitchers in next years free agent class.