It was a question of a player to be named later or cash when Mike Carp first came to Boston. However, according to an earlier report by Tim Britton and an update from Providence Journal writing mate Brian MacPherson, it's going to be cash that finishes off the Mike Carp trade. See for yourself:
Update on the Mike Carp trade: It is expected to be completed by the end of the month with (as @timbritton reported) Seattle receiving cash.— Brian MacPherson (@brianmacp) March 8, 2013
Carp is busy fighting for a bench spot with the Red Sox, and is already on the 40-man roster. However, simply being on the 40-man doesn't assure him of a spot, as the Red Sox essentially are sending cash to the Mariners in order to be the ones looking at Carp all spring. If they don't like what they see, the cost was low, and the idea of a sunk cost will be that much easier to deal with.This is especially true with Lyle Overbay in camp, as he is the better defender of the two, something that could turn out to be the point of separation for two guys vying for a bench spot on a bench that is expected to already have bats.
Our photo system is predicting that it will be Lyle Overbay making the Red Sox, if for no other reason than there is visual evidence of his wearing a Boston uniform this spring, whereas Carp is only available in Seattle gear. This seems like as safe a way as any to predict roster moves, really.