My math may be a bit rusty, but if memory serves well, I do believe that "3" does not equal "more than 3". I think the idea here is that for a lack of active clans, you can sign up teams of three players, regardless of the clan they're in, in order to have enough teams for a remotely serious tournament. Even though it might be a good idea to allow each team to sign up a spare 4th player if one of their squad can't make it, this would make the 4th player in question unavailable for any other teams that are trying to form (at least, that's what would be most logical, it would be rather silly if a player could hop from team to team throughout the entire tournament), which kind of kills the idea of having enough teams for a decent competition.