Thanks for all of the suggestions. I wasn't able to make changes until last night, and overall they were very helpful and led to a much better deck. I have modified the UG deck to reflect my current list. Overall it ran pretty smoothly, and I went 3-1 overall, losing 1-2 to the eventual winner. If I had the Sylvan Caryatids I would have stood a much better chance against the red aggro deck that beat me.
I cut the Gyre Sages, Frostburn Weirds and Cloudfin Raptors. I think that you're absolutely right that I should play to my strengths, and my strength should not be in trying to out-aggro someone. Things went much smoother with the evolve creatures gone. I couldn't get Sylvan Caryatids, but I think they would be the next change that I would like to make to the deck. I added four Elvish Mystics, and they were great for getting Polukranos out on turn three or the Prophet on turn four. They were much less clunky than Gyre Sage. If Gyre Sage has a deck that it works well in, it is not this deck.
After my changes, I ended up at three Horizon Chimeras, three Prophet of Kruphix, three Wall of Frost and four Polukranos. I think that those are the right numbers for the deck. Prophet of Kruphix completely propelled me ahead whenever I cast it. It meant that I could cast Divination or a creature and be confident that I could keep up mana for countering on my opponent's turn.
For spells I went to three Divinations, reduced the bounce element, and added in Dissolve. Between Jace, Prime Speaker and the Divinations, there was plenty of card draw. I would love to cut the Disperse for another Cyclonic Rift. I'm not sure if any of the Simic Charms should be Cyclonic Rifts, as the +3/+3 mode was very useful as well.
Aetherize was amazing from my sideboard, and Fog let me win one game that I otherwise would not have won. In an ideal world the Pithing Needles should have been Cyclonic Rifts #3 and #4 and two more counters.
I went in to the tournament thinking that I would trade off the deck after I was done, but I had a lot of fun, so I'm going to try to make that trades that I need in order to get a better mana base and the few cards that I'm still missing from my ideal build. As a side note, there were four other players also running UG decks, though all fairly different from mine.