I think I would like to see the Cubs get the best rental pitcher they could without giving up a top 6-8 prospect on the team. That could be a guy like Kelly. Others to consider are Lugo, Soroka, Morton and even Gallen. I also would be ok with them adding a bench bat/3rd baseman as a rental as well. Probably not Suarez, since he might cost too much for a rental. But Castro would be a good pick up. They can add enough to win this year and still keep their best prospects if they stick with rentals. And unless Ryan or Gore are realistically available, I would rather do that then trade for just a decent pitcher (Keller, as an example) and have to lose a top 5 prospect just because they have control over him a few years.