As noted earlier, Nate Robertson is due $10m in 2010, the consequence of an earlier three-year contract. How much of that will the Marlins be paying? According to Ken Rosenthal, not much.
Tigers paying $9.6M of remaining $10M on Robertson's deal. In other words, Marlins get him for minimum.
Getting Robertson for $400k makes this virtually a cost-free addition for Florida, and, if ineffective, they'll be able to bump Robertson to relief or kick him off the team entirely without feeling like they wasted a lot of money. With Andrew Miller, Sean West, Clay Hensley, and Rick VandenHurk hanging around as starting options, among others, Robertson will certainly have to prove himself in the early going if he wants to stick in the rotation.