This is what I think must be the reason why Fnatic just crumbled against LOUD.
1stly They somewhat had some pressure in their minds And were to desperate to win 3 Trophies in a row. Like How some Bowlers in cricket get this feeling when they are on Hat trick.
2ndly though Fnatic is a Very prep heavy team still they looked a little lost like they were doing quite obvious things and were playing quite similarly. Like they were executing in last 20 sex which costed them many rounds.
3rdly having a perma ban really pinched them against as according to most analysts, LOUD already won the map veto. Like LOUD dominated PRX on Split (PRX's one of the best maps ) and LOUD's Hevan is also quite strong and we all know about ascent as their best map. So with pearl going out of the map pool It might favour Fnatic but catch is Breeze is coming back and Breeze has been there perma ban in past.
4thly Losing too many Bonus and Pistol rounds . Like Last night Fnatic won only 2 Pistol round and lost almost every Bonus round .