I think pillars are more specific then that. Nobody can beat the Straywood Beastmaster in swarm play because no one else can cast two creatures a turn while also moving forward. Swarm works, and the beastmaster has the best aggressive swarm.
Someone else probably has the best defensive swarm, I'd estimate druid, summon vine snappers and a thornlasher and the teleport the enemy mage in. Defensive swarm is essentially "pit" strategy and I think pit is another pillar.
I don't think SBM is unbeatable at swarm play, or even the best really. I'm not sure why it's relevant that the SBM can move forward while casting creatures...if anything, I wouldn't want him near the fighting since most of the mana is being spent on creatures and not defensive cards. I usually keep a mage that is swarming at least 3 zones away from the opponent, and only after I play something like Nullify/Cloak of Shadows/armor/etc will I move it closer. Specifics vary depending on how specifically the swarm works for that mage.
Swarm play is a lot more than just a mage's abilities; it's also their card pool and match-ups. I think in that respect, the mage that can swarm the best is actually the Bloodwave Warlord with Necro as a close second. They have a ton of great support cards for the strategy, like the only 2 rings that reduce spawnpoint cast costs and access to the key school-exclusive armors Harshforge Plate and CoS, though I think the Warlord's access to Conquer sets him apart. The hardest counters to swarm other than zone attacks are conjurations (Obelisk and Orb), and being able to outright destroy them without committing attacks (or only a couple for guards) is huge. Conquer is also just a solid play on enemy crystals or whatever.
The orc Warlord's veterans also give him an innate advantage vs other swarms to the point of making most level 1 creatures unplayable against him. You pretty much have to play level 3 or higher creatures, which are efficient to control with curses/attack spells. A couple Agony solve the worst offenders unless your opponent is psychic.
I'm not saying that the Straywood BM is poor at swarming; obviously that's not the case. Based on my experience, though, a couple other mages execute a more robust swarm. Thus, I think A. West's success at GC has a lot to do with the fact that he read the meta very well, because if you look at his deck, it's pretty straightforward. He planned for most problems, though I think he would have been in trouble if Flame attacks/incants had more of a presence in the tourney.
In terms of "pit" strategies, I don't really consider them high quality. It's the same vein as wall of thorns/push cheese in my opinion; exceptional if your opponent doesn't have a tuned deck, but poor if he does.
