In a tournament as big as this one, the best barometer you can manage is to look at what the players with three byes are playing. Starting the tournament at 3-0, they can expect to face a more homogenous set of opponents. As a result, they can choose a deck to trump the popular designs. If they choose wisely, they will be greatly rewarded. What follows is a rough breakdown of the decks piloted by those who have it easy today.
Mono-Black Control - 20
These dedicated Speculation builds seek to take full advantage through Catalyst Stone, Roar of the Wurm and Grizzly Fate, as well as some utility one-ofs. The Fate, in particular, is a card that gives most decks fits. Mental Note and Careful Study ensure threshold, and better, dig to Wonder to make quick work of opponents.
Upheaval-Infestation - 5
After Kai Budde's Upheaval-Psychatog deck fell flat at Grand Prix - London the Upheaval-Infestation version seemed to pick up the slack. Gabriel Nassif took it to a respectable eleventh place. Borrowing most of mono-black's creature control, it survives to the late game where it can win in one spectacular turn. Cabal Therapy makes sure Envelop poses no difficulty.
Mirari's Wake - 4
Blue-Green Threshold - 4
Straight off Dave Humpherys 6-0 Worlds performance, this little number runs the most efficient creatures in the format. Standstill makes a good combo with undercosted dudes.
Blue-Green Hybrids - 3
These decks borrow a little from both the Madness and Speculation schools, sometimes with Werebear, just for fun. The tutoring power of Speculation compliments the aggressive beatdown, giving the deck a catch-all for bad situations.
Blue-Green Madness - 3
Enablers, madness creatures, Circular Logic and bounce. These decks don't give the opponent much quarter off an early stumble.
Punisher Blue-White - 3
Red-Black Sorcery - 3
These decks will definitely delight, provided they make the cut into Day 2. Fortunately their pilots are expert enough to make that happen. Keying off the power of Recoup and Burning Wish, they otherwise resemble a mono-black control deck, with one exception: Four main-deck Earth Rifts to stand alongside Rancid Earth.
Miscellaneous - 4
Surprisingly, only one each of green-white madness and blue-black Braids are being played by those with three byes. Rounding out the "other" group is a very rogue blue-black-green Holistic Wisdom Control deck, and a mono-red Dwarven Bloodboiler deck, as played by Dan Paskins at Grand Prix - London. Perhaps mountains should not be so quickly counted out of the metagame.