1) iG been playing "uncharacteristically" bad ever since
Fact is no one alive knows the state of IG right now so it's pure speculation. Their Summer split was a mess all in all. First, Rookie took a month off to tend to a family emergency and looked bad to mediocre upon his return. Second, Ning inted his face off and had internal drama so he got replaced outright by a rookie. Third, Baolan was also inting his face off and briefly got replaced before returning. Now: they have a new jungler entirely and Rookie kind of looked like his old self in the gauntlet. No one has a clue what spending a month boot camping is going to do for IG. If Rookie is remotely back to his standard level of play and Leyan at least has a base level of competency in regards to coordination with his teammates then they could win the whole tournament. If not? Well it could be a 2-4 group stage showing and they're out immediately.
They are the ultimate wild card this World's tournament. No one knows how they'll look because of how many variables with the team.