Multiple rounds, statistically, are going to kind of snip off the ends of the bell curve here.
Teams may pull an upset, which is unlikely, so 2 in a row is astronomically unlikely.
The best teams, even if they're truly best, are going to have to prove it multiple times against teams they have a <70% chance to beat (probably), which makes 2 wins vs teams that good at under 50% likelihood.
It helps teams that are good enough to avoid upsets AND beat #1 on any given day. A race to the middle (of the top cluster), if you will.