I think the result in this match boils down to a couple things:
1) ATL did their homework on Toronto. They did scouting, they watched them play and learned that they are a divey team that likes to throw surprise picks at you. They predicted that they were gonna try to be unpredictable if that makes sense.
2) Toronto was not ready for a team to play off the current meta to shut them down. Their comp was basically tailor made to shut every one of their players down, and they just couldn't find an answer. ATL has weeks of preparation that Toronto didn't.
3) You could also argue that it all comes down to ATL just being that good. And credit to them, I think they are a top tier team, but I really believe you need to give a lot of credit to the coaching, and really analyzing what Toronto could throw at them ahead of time.