Player A is a bonjwa who can beat almost anyone.
Player B and Player C are good players with about 50% win rate in proleague. B is slightly better and would likely take a Bo3 off C.
Player D is a B-teamer who cheesed his way through prelims.
The first round is:
A vs D
B vs C
Since A is so much better than D, the second round will be (assuming B beats C):
A vs B
D vs C
The final match is a rematch of B vs C, again due to skill differences.
Say C wins this match. He's a little weaker, but players often lose single sets to slightly weaker players. C is now 2-1 and advancing, and B is now 1-2 and out of the MSL. The problem is that C never proved he was better than B. They went 1-1 against each other and never played a common opponent.
I'm not going to check this for a few days since I'm not caught up on the MSL yet and I have a feeling this thread's going to get spoiler-y.