Rosenthal makes the most amount of sense for me. With his age, talent and situation on the Cardinals, Rosenthal could be a stud reliever now and a solid starter in the future. He may be the type of player that changes the future of your team, while Morton and McCarthy are just stop gaps. Span is interesting, but don't mortgage a future stud player for a solid starter now. I think you can get Span, or a comparable player, in a later round of the draft, but Rosenthal's talent may be something you regret letting go of.