Thinking about this trade for longer, I feel the points raised in this thread make for a strong narrative as to the reasons why the Royals did this now, and the ways that this could help, perhaps even beyond face value. Also, I didn't consider the Davis factor much... I mean, still with youth on his side, his strong results in relief really could also be a sign of a pitching advancement than just a role change. If the scouts see something they like with him, the option years on that contract could turn into the most valuable thing in that trade. He certainly would not be the first talented pitcher that took some time to become a rotation force, heck he wouldn't even be the first guy involved in this trade that fits that description.
At the same time, the Reds didn't give up the top hitting prospect in baseball for Rolen. They essentially gave up some stuff that seemed overhyped at the time, and in hindsight, the players looked even worse. Time might very well tell the same for the package the Rays received, especially Montgomery, and Leonard, but, I think a team like the Royals needs to take the chance on the Myers' of the world, because for a smaller market team, guys like that gives a team the best chance to be a sustainable force.
Perhaps becoming sustainable is a few zipcodes out of the dictionary for the Royals considering they still need to make a few steps just to become relevant again, but man, if Myers is that good, this is going to hurt 10 times worse than the success they could get out of it on the other side of the coin. Also, the timing of this could be woldly inappropriate. Two years from now if Hosmer/Moustakas and co. establish themselves as being able to turn the Royals into big time contenders, maybe trading the high end prospects to get the cherry on top makes more sense. Or maybe with their system they can do both? It certainly would seem much more palatable right now if Francouer was actually a 'thing' rather than being a replacement level part. This certainly wasn't quite the same "trading from a positional surplus" that the Reds did in the Latos deal. The timing of the Latos trade, and the parts we gave up certainly seemed to fit perfectly with the rest of the puzzle that Jocketty had put together.
I can't argue much with what the Rolen comparison did for the Reds. If Shields is able to do the same for the Royals, then they are not going to regret this one. But I feel like there must have been a cheaper price to pay for that effect without removing one of their best chips that also fit their roster well (but at the same time, I can't think off the top of my head another available piece that could have performed that role so well).