The exact rules for the automatic question and answer bans are not public, we know some general principles behind them, but not much more. I agree that some automated mechanisms like this are necessary for a site as large as Stackoverflow, but I'm wondering if the exact details really need to be secret for the bans to be effective.
The reason why they are secret is, as far as I know, to prevent users from gaming the bans. But I wonder, from what we know there isn't much a user can do except to provide some good content in the categorie he isn't banned or to improve the existing content enough to gather some upvotes. I might be wrong as I don't know the details, but I don't see how you could game the ban without accidentally posting good content, exactly what should be encouraged. Knowing the details could make it more effective to lift the ban, as you would know exactly which criteria you need to meet. But you still would have to improve your posts or add some new ones.
Is the secrecy necessary for the bans to be effective, or wouldn't they work as well as they do know even if all the details were known? While I think they are necessary, I'm a bit uncomfortable with such drastic measures that cannot be reviewed by the community due to the secrecy.