Gonna go ahead and drop this here:
Ideally the whole rank system would be passive and hidden so that nobody worries about their rank. In fact, it's not a measure of skill, it's a measure of attendance. Really it's actually a measure of failure to attend properly, so there's no reason to divide up "A" from "S" from "B", really, since only the most demanding of mods would bother with ranks that high. At that point, you might as well be invite-only from who you think is a good player.
Here's what matters with rules infractions; how fucked up the game was. There's no reason to try and put them into categories when the answer is simply to divide them based on what the mod had to do to continue the game.
Warnings: Not major enough to warrent any action other than the mod issuing a warning. Prods are warnings. Might also be about revealing too much info in a "bah" post, threatening to break the rules, or whatever else you kids are going to come up with next.
Minor rules infractions: Major enough to warrant a modkill or force replace, but minor enough that the game can continue in some fashion. This includes flaking!
Major rules infractions: Major enough that the mod deems the game ruined and decides to stop it prematurely. Only given out if one particular person or aligned group were directly responsible for the game stoppage. If many people were involved but none of them did anything bad enough to stop the game on their own, they get minor rules infractions only. This is so that, for instance, a bunch of flakers don't all get stuck with major rules infractions, but a group of players all teaming up to make another player lose for out of game reasons do get major rules infractions.
So personally, I think there's should be only 4 categories.
Good:
No problems whatsoever or extremely infrequent problems. 1 or 0 warnings
Average:
No major issues, but does need warnings every so often. 3 to 5 warnings OR a single minor rules infraction with 1 or 0 warnings
Not good:
Probably going to be a nuisance, but the game will be fine even if they do fuck up.. 6 or more warnings OR a minor rules infraction with 2 or more warnings OR a single major rules infraction with 1 or 0 warnings and 0 minor rules infractions
Horrible:
Probably going to ruin the game. 3 or more minor rules infractions OR a major rules infraction with 2 or more warnings OR a major rules infraction and a minor rules infraction.
Rankings should be measured in semesters. They should roll over onto new ones, but the conditions that gave the rank out in the first place should not. For instance, if in 6 months Pandarsenic gets 3 warnings for lurking, he drops to Average the moment the third warning is issued. However, when the new semester starts, Pandarsenic stays at Average but has no warnings. If he keeps having no warnings for the new semester, his rank will become Good again for the following semester. I hope this makes sense.
PPE: STOP POSTING SO FAST, JEEZ