The VAC wave did impact but matchmaking ranks, but certainly not as much as everyone seems to think. Thinking about it logically, the ban wave would have opened up slots previously held by a cheater, but a Nova 3 couldn't suddenly become DMG, as they'd still have to compete with those who earned their DMG rank. You may have been able to get one or two ranks higher, but you still improve the more you play, it doesn't all just come down to the VAC wave.