A very public explanation was already offered on their failures. A complete change up in their roles and play style was not a good fix for them. Since going back to a Snax/Pasha AWP and Taz IGL, they've now steadily increased their results. Solid LAN events (Even with a loss to RNG) with an honestly better online play from VP since like 2015 are all perfectly valid reasons to see them as a top tier threat.
They are known to never be the best team in the world, but the gate keepers to that position. Always rising to the level of the best teams out there. Coming up against SK at Epicentre proved that is happening again.
Right now the skill level of the top teams is pretty shit, so an unstable VP that is on the rise, yes, they are a top tier team. If they played at this level back during Las Vegas, when Astralis, SK, North, were playing great, no they wouldn't be. But right now, it's hard not to peg a team that can threaten LANs again as a top tier team.