As with the Giants a few years ago anything can happen in the playoffs. If this team gets hot like in May, I could see them going for in the playoffs. I think you make a move to win the division and that should be the goal.
You shouldn't rely on rebuilding a few years from now, especially with pitching as two of the arms you are relying on could have TJS and be gone just like that. If you have a shot you should go for it because you may never be in that position again. That being said I'm not advocating giving up the farm for a rental, just that you shouldn't rely on a young rotation and always build for the future.