More extracts from my Bandai postings that I find useful:
A Swiss + cut event is designed to largely negate the effects of luck (due to the fact that it's possible to make top cut with 1-2 losses). In a deck with 11 0 drops and 3 Tobis (Tobi counts as reducing deck size by 1 - he actually should contribute more than that to probability but we're being conservative here), there is approximately a 18.1% chance of not drawing a 0 drop on a hand of 6, and a 24.6% chance of not drawing a 0 drop on a hand of 5. Assuming that the probability of winning with a hand of 4 is 0, that means there's only a 4.4% chance of drawing a hand that cannot win, no matter the skill level.
And let's assume that the deck is poorly constructed enough that 15.6% of the time, the hand will be unplayable or the cards drawn will do nothing. That means 20% of the time, a player will lose and be unable to control it at all.
6-2 with good breakers usually makes T8 at a 8 round event, 6-1-1 and 6-0-2 always will.
Even if you fail to win in 25% of your matches, you still make top cut.
Now take that earlier 20% - if a player is skilled enough, they'll be favored to win the rest of the 80% of the matches because they are better than their opponents.
But here's the kicker: bad luck doesn't just apply to yourself - bad luck also applies to your opponents. Therefore they also have that 20% chance of flat out losing a match due to a bad draw.
Applying the proper probabilities, here's the breakdown of a match between a good player and a bad player.
64%: Balanced game - good player wins (80% * 80%)
4%: Crappy draws on both ends - good player wins (20% * 20%)
16%: Bad player has a crappy draw - good player wins
16% Good player has a crappy draw - bad player wins
The good player should be expected to win 84% of the time, not just 80%.
Of course, the actual good player win percentage should be even higher. What separates a good deckbuilder from a bad deckbuilder is that the good deckbuilder reduces that 15.6 "unwinnable" percentage by tightening up the variance of the deck. What separates a great deckbuilder from a good deckbuilder is that the great deckbuilder will skew the draw distribution of the deck in order to create auto-win draws where the opponent can simply do nothing, no matter how they draw.
Is it possible for a bad player to be super lucky and make top cut, or a good player be super unlucky and miss top cut? Of course - it's possible, but improbable. Over time, all that shading of probability leads to a situation where good players should be able to top cut consistently due to the Swiss + cut format.