Just depends on when you climb the KC Cup. On the first day, there were 80% CA in the upper ranks. Now it's dropped significantly as the CA players either reach max level or switch.
After taking a break for a few days, I climbed from 15 to 18 this morning, and the most common deck by far that I saw was AG. I actually don’t recall seeing any CA decks earlier today, which is weird.
Can't you read above? Most of the brainless mind scan CA decks already got DLv20 so obviously you aren't gonna see them, whereas AG which take much longer to reach 20 you'll see a lot of.