Update: Check out this tweet from MLB.com's Pirates beat writer, Jennifer Langosch:
Update (12:21 AM): Apparently Marte was pulled for "team reasons", probably being disciplinary. Maybe he didn't run something out or said or did something else that his manager didn't like, so they yanked him in the 5th. You shouldn't do that this close to the trade deadline, it makes the bloggers go nuts.
Marte is still a Pirate farmhand... for now...