As you said, it's really just an unwritten rule that gets mistakenly broken every now and then. Not a big deal. A member will start a gamethread and continue to do so until the Sox lose. It could be as long as one game or a 15-game winning streak. If the Sox are coming off a win and the poster who started the gamethread for that game does not start it in time for the night's game, anyone can start it. We normally give until about 10 minutes before game time before someone else can jump in or the correct member yells last minute "HOLD ON A SEC I'M HERE TO START IT!" (lol, that's been me a few times.) If said member never shows up, whoever starts the thread that night now holds the mojo. For example, even though Dutchy started it last night (which is not a problem Dutchy, lol, don't sweat it), we won, and he would continue with it. HighMileage now, even though he interrupted Dutchy, must now start tomorrow's game thread if the Sox win. And, seeing how he's a Royals fan, I hope he starts the next three threads too. That would be a little ironic.
After a loss, it's free. Anyone can start it, even newbies if they'd like. We just ask that the game thread not be started until a reasonable time on gameday, so we can continue discussing about the most recent game before gametime.
Not that complex, just a little tradition that kind of popped up back in 2004 I think to have some fun. We know where that got us!
Anyway, back to the game thread.