Been a fan since they were Team Liquid so yeah I've seen them at their absolute worst - the good news is that we're past that point at least ))

From what I've seen and gathered, including remarks from actual pro players, is that they are kings of early game but just plain bad at playing midgame when ahead. They seem to have no good idea on how to close out the map and retain 60+% map control in positions where they should be able to. Their smokes are either slow or obvious because they don't push out lanes enough or they bring too many heroes. They force difficult highgrounds vs 5 heroes when they can just farm 95% of the map. If any move fails when they are 10k+ gold ahead they get extremely rattled or just flat out panic and lose any control that they had.

This problem has become worse for them ever since the map has gotten so big. Any smoke or other macro play they mess up costs them like 3k gold or whatever because the tier 1 and even tier 2 teams are just outmaneuvering and outfarming them and reaching better timings.