RNG may have lost a couple games to C9 and VIT, but that doesn't suddenly make them weak.
They won every international tournament this year. Losing individual games means very little in a best of 5 - which is what they get from here on out. They'll learn and adapt. They did against C9 in the tiebreak, didn't they?
Afreeca, however, did come out and go 3-0 today. So likewise, they learned and adapted. I actually hadn't watched that group at all, so I paused at this point writing this post to watch the game against G2 from today to get an idea of how they're playing.
Their 4 man tower dive bot lane was beautifully executed.
The Ryze tp to try to save bot tower was questionable (maybe they're hoping G2 wouldn't realize they had the damage to burn through it, more likely they didn't realize G2 actually had the damage).
The Gragas death at cloud dragon was very questionable (they very much overestimated his tankiness).
They punished G2's mistake of going for Herald HARD
Afreeca's vision to this point was INSANE. Even when behind they had vision everywhere, regular wards probably a few pixels outside of the range of control wards. They knew where G2 was at all times.
They react to the aggressive early baron really well. Their team really outscales G2's, and they're much weaker at this point of the game (due to team comps). Very smart of G2 to force the Baron, but also well replied to.
Afreeca got an amazing pick on Aatrox, and turned it into a Baron + 3 more kills and basically win the game at that point.
One more teamfight that Afreeca just dominates now that they've scaled (you can clearly see the difference, Gragas is now tanky enough to survive the initial engage, too many cooldowns are burned trying to get the kill and Afreeca wins).
So given that performance? Yes, Afreeca seems to have figured it out. Sure, it's just one game. Maybe their other 2 wins today weren't as good. Honestly I'd say there were 2 mistakes by Afreeca in that game. Both in the early game. One with almost no consequence (Ryze TP) and one with a small consequence (a death and a dragon). Meanwhile they punished all of G2's mistakes super hard.
So... well, I don't know. KT, Afreeca, and RNG all still look really good.
I don't think it matters that Afreeca went 4-2 with their losses in week 1, but RNG went 5-2 with their losses in week 2. 2 losses are 2 losses - games where they underestimated their opponents (or their opponents played well and used a good and unexpected strategy to win).
It shows that teams like G2 and C9 (read EU and NA) have a chance against Korea and China now, but those countries are still the favorites.
I'd give all 3 of those teams equal odds to make the final though. Whichever team avoids the other 2 in semis will be a large favorite to make it to the final. Let's hope RNG meets KT, and C9 gets a chance to play Afreeca and IG.