Crackers mostly post the cracks to IRC sites, cs.rin.ru, and private torrent sites. Repackers are the main way releases make it to the mainstream torrent sites.

Repacking isn't that complicated anymore, it's more about reputation. There was a time when games were big and internet speed was slow so saving every MB of size was important. Repackers would reencode video files and find other ways of dramatically reducing the file size. Nowadays they don't do a lot of that, but repackers are still important for casual pirates who just want to easily play pirated games and not worry about malware.