O'Day would be amazing. O'Day, Cecil, and Osuna at the back of the pen, and to a lesser extent, Loup and Sanchez, would make for an awesome pen. Getting 5-6 innings from the mediocre rotation and then turning it over to a lights out pen featuring 3 elite arms would be pretty effective.
What do you think St. Louis is thinking? You don't hear much about them as a potential destination, but they have a need, it's probably just a ~10M raise this year, and Holliday is off the books soon. Is it just aversion to the risk of a 10-year commitment?