Carlos should stay in the role he's in because that's more valuable than closer. Actually, it would be best if they just used him in the highest leverage situations, regardless of inning (i.e. one run "saves", runners on in the 7th in a 1 or 2 run game, whatever), but that'll never happen. I'd rather not waste Marmol with a 2 or 3 run lead and nobody on for a good bulk of his appearances.