Orgazational depth is important, especially when a lot of the 3B prospects are quite a ways out of contributing that we're not sure what they'll develop into. For example, what if the Giants had traded Bumgarner (looking like a decent pitcher) for Freddy Sanchez, instead of Tim Alderson? Similarly, a couple years ago it looked like we had great depth in the OF with Ellsbury, Kalish, Reddick, and Westmoreland, but Westmoreland had brain surgery and Reddick fell off the map. What if the Sox trade Middlebrooks, Cecchini breaks an arm, Vitek doesn't pan out, and Youkilis doesn't age too well?
I would not mind moving a pitcher like Weiland, but I'd be concerned about moving someone like Ranaudo, simply because his upside is so much higher and the Sox don't have a lot of need for prospects that project to be middle-of-the-rotation types.