I guess you'll have to forgive my ignorance. Without some sort of rational explanation, I'm baffled that a single match would require 300MB of data transfer, as well as the fact that the game apparently moves 1GB around "very often."
People have already dug deeper and found out that it wasn't the match itself, it was downloaded after the match. Looks like a bug with them fully refetching all store skins and models every time the user lands into the main menu after a match.
