I think it's a bit unfair to say that IMT didn't know that the tank meta was coming. The resources were everywhere and everything pointed to that direction, and it would be silly to think that so many casuals know this over IMT's analysts. Even though Pobelter said in the postgame interview that they misread the meta, I think it wasn't due to not knowing that the tank meta exists. Either way, Pobelter at least implied that IMT got the picks they wanted.
		
		
	 
Yes, I am aware of that and that's why I put the emphasis in ''having only 1 teamcomp''. Despite the fact that, for better or worse, the current meta is pretty much defined by what is played in Korea, and the western teams are all basically following what is used there, I accept the fact that it is possible to innovate in some instances. For example, we saw CLG play Rageblade Tristana on Saturday, and EU teams trying Kassadin as a Lissandra counterpick. But it wasn't their only plan, and as soon as the teams saw that their unconventional pick didnt perform as well in stage as in scrims, they played something else.
So in that regard, I would have been ok with Immortals trying to play their 'anti-meta' comp, as long as they had a backup plan in case it didnt work as well as planned. On the first game, despite the 'Deatbush' thing and all that, Immortals had the least early game and jungle control in the entire split. That's why I blame the coaching team, because they had no backup plan for Rek'sai getting banned and Reignover having to suffer an unfavourable jungle matchup. Immortals should have looked at teams like ROX and G2, which have also been playing a snowball/skirmish style in their regions, but with much more flexibility in their picks.
For example, this happened to Cloud9 as well. They had a good gameplan prepared that involved using Twisted Fate and to a lesser extend Gangplank to create cross-map plays and advantages. It worked well one game, then Twisted Fate got banned the rest of the series, they had no backup plan and got destroyed.
Edit: Montecristo's analysis was quite accurate:  
Edit2: Monte's in my head help :( 
https://twitter.com/MonteCristo/status/719557150305968129