Deep breaths people.
Blizzard has all the logs, not just these, all of them, for every fight. They also have data engineers that are going to be pouring through them and figuring out what the data is saying.
Is there an overrepresentation of Fire mages, because fire was perceived as the best spec, maybe. Blizzard will figure it out.
They have guys paid six figure salaries looking at the internal blizzard logs. Hell they can even cross reference past achievements (mythic kills / world firsts etc...) to figure out if a "skill" metric for the player and adjust accordingly.
They have stated, that they have barely even touched on balance so far. They were waiting for data, data we give them when we raid. Give them a few weeks to figure out the data, and I expect heavy balance changes in the next few weeks personally.