Obviously the deck is relatively good for you to have performed so well this past weekend. But, that being said I think there are a few areas for improvement.
First off, this certainly isn't like the G/R devotion list that is in need of a crap-ton of mana to dump your entire hand every turn, so I wonder whether you need that ramp or whether perhaps you could use some of those spots for other cards. Specifically, I like the Sylvan Caryatids as they offer blockers AND ramp, but Elvish Mystic strikes me as horribly under-performing for you. That and a top decked mystic on anything other than the first 3 turns is just weak.
Personally, I like what you're doing with the Ghor-Clans and Flesh // Blood. The idea that you can swing with Polukranos, pump him, and then still zap them for 9 more for only two more mana is quite appealing (hard to believe nobody else has noticed it). So if you were to drop the mystics, I can see where adding two more Flesh // Blood and perhaps 2x more Bloodrush would be effective (I'm thinking either Rubblehulk or Zhur-taa Swine as they both lead to a substantial pump), although the trample from Ghor-Clan is really what makes it so good. To that end, perhaps 2x Nylea, God of the Hunt could prove beneficial.
The only other area I can see for improvement is the SB. The 4x Mistcutter make perfect sense and I'm good with that (although I would perhaps say to go down to 3x). I'm not so sold on where Shock is going to be sided in and will make a difference. Destructive Revelry is really misleading as I would likely run Fade into Antiquity over them - getting rid of Thassa or Nylea is a pretty big deal. I'm also not sure I see a scenario where Chandra, Pyromaster would come in... as you're already generating card advantage with Garruk, Domri, and Xenagos. So I can see a fair amount of wiggle room here to drop stuff and find pieces that will be more beneficial to your specific match-ups. If I were to run with a SB for this deck it would likely look something like this:
2x Pithing Needle - stop Elspeth, Jace, Ashiok, Pack Rat, Mutavault, etc etc
3x Mistcutter Hydra - you know the mono-blue matchup
2x Plummet - a good call, as it will take out a Desecration Demon in a pinch
2x Fade into Antiquity - exiling, scrying, and just for one more than Revelry... yeah I'd do that
2x Bramblecrush - destroys PWs, artifacts, enchants, lands, you name it... this card is sort of a skeleton key
2x Mizzium Mortars - you could talk me into these being Anger of the Gods - your aggro matchup is a bit weak from what I can tell
2x Ruric Thar, the Unbowed - if you ever wanted an anti-control card, this guy is it... but you'll want 2x as you'll almost never draw him with only 1x OR, might want to draw 2x in long games
Anywhom, I hope some of this helps. Props to ya for finding a different way to attack the R/G build.
Oh yeah, I almost forgot... if you want something else totally off the wall, I played against someone using Savageborn Hydra the other day and it was quite the nuisance. Make even a 3/3 one and then the next turn swing, bloodrush Ghor-Clan on there, you'll hit for 14 and can cast Blood to do 21 damage in a single turn... some food for thought...