He played rly good even tho KC looked like the shittiest team in the world. He was one of the first gekko mains when they played goofy gekko meta???
Now KC is shakey but he looked solid
They didn't get gradually get worse. They just got exposed later into the season for not being able to midround and people started countering their set strats, which meant they were an easy opponent. d00mbr0s said on his first Plat Chat episode that Karmine Corp were an easy team to prep for, and this is why. All you really have to do is counter their strats and you win because that's what they're relying on so heavily—because they can't midround.
idk too much about karmine corp and magnum, but if midrounding is a big issue he doesnt necessarily have to leave, they can get a vocal midrounder
many teams have succeeded by having 3+ vocal players
edit: karmine corp also have 3 duelist players. maybe that can lead to a midrounding issue since duelists usually have less calling experience