The thing that makes their group draw so good, is that they didn't have to scrim/prepare specifically for ANY of their group opponents. They could be scrimming Bo5 SINCE WORLDS PLAY INS Stage, while FNC for example had to be preparing SPECIFICALLY for RNG and SKT, until the entirety of the group stage was over.
FPX had the luxury of time on their hands. AND OF COURSE the luxury of showing almost NOTHING of their true potential in group stage.
I think that really let them practice drafting A LOT more than other teams. Yes they didn't know exactly who they would need to face in knockouts, but they had an idea of what teams would trouble them potentially, they had the time to perfect their drafts against the 3 potentially 4 teams that even had a chance to beat them in the first place. Also, they obviously would have a good draft vs IG being in the same region.
Worthy champions don't get me wrong, I'm glad they won it over any other eastern team. But not the undisputed best team in the world like IG was for last year's championship, when you just couldn't see any team beating them at the time.
If FPX was more of a known entity and their weaknesses exposed more, I can see them losing to many Korean teams, IG and maybe even Eu. I am talking about going forwards to MSI, LPL etc.