Papelbon is one of the areas I don't have a problem with. The ultimate goal here is for him to be a starter and to do that he needs innings. He pitched 129 innings in 2004, 148 innings in 2005 so development wise, he should be in the 170 range this year. However, as a closer he's only on pace to throw 81 innings, about half of where he should be.
With his age and his arm, I don't think him wearing down is really a concern.