Cvg has over 20,000+ bans
http://sourcebans.convictgaming.com/index.php?p=banlistFrom permas to monthly to hourly.
Majority of new players that play on zps decide to play on the most populated and popularly known which would be Cvg. When they play on their server that player will play for a bit, and suddenly get himself banned for some reason. Which would likely make him/her rage from ZPS forever.
We can all agree that the decline of new players is mainly because of Cvg, and maybe other abusive servers.