Even if this is true, pain is one of the unpredictable teams that can take a game off anyone. They went 3-1 against Liquid at the Birmingham Major.
Actually, "weaker" (top 20) teams regularly do take games off better teams so I don't think there's much evidence for an exponential skill increase between teams.
Looking historically at team ELO and how squads have gone on 27-series win streaks, this is probably right. Though I think the gap between "low-tier" TI teams and TI winners is getting much tighter. Group B at TI8 was so close the difference between upper-bracket and lower-bracket was 1 game for most of the teams.
