Here's my awesome paintness of the best tactic I know of for holding B from the Russian side. This is of course if advancing and taking the next flag is out of the question temporarily or permanently. It has never failed me. Ever.
You will always get there ahead of the US btw for those that don't know.
Primary's are the positions you need to have held from order of importance A>B>C (Not flags) for position and where your better fraggers should be.
TUGs should always be used on A and B. Always. Spawn recon if you have to, you can kill guys that you know are coming with a pistol a lot quicker than you can guys you don't know are coming with a rifle. Then you will also have a spawn beacon at your disposal.
Position "A" can absolutely control metro if used properly. You suppress the side stairs to the locker room and you control the rear escalators. You also support position C if they start to make a push on the right.
You will never be killed by guys coming up the escalators if you use the position correctly. Don't just run to the top of the escalators and firefight back, farrrrr to many people try and do this and only a few can actually sustain the fight. Always fire down from the side or fire down from the "top" of the escalators. Once you do this to them a couple times they get discouraged big time at trying it anymore.
For those of us who like the sniper rifles with acog this is a great spot. You will get head shot after head shot while they are piling up on the left trying to get into the locker room.
Secondary's are if you have enough people to actually fills the spots or if the randoms on your team are actually doing work. The corner point above the escalators can be absolutely abused with a shotty and a medic if your "A" position is doing his job. At the same time if they push hard on the stairs all you do is side step out and let them have it.
Extremely easy tactics with positions that all have cover and a large amount of surprise. If enemy pushes any direction one of the other positions can cover as long as they aren't down to their last guy.
It may seem like A is a little weak if they bum rush the escalators but seriously, don't underestimate the power of being above someone and behind cover. You will end up killing 3-4 guys in a single mag, switch to your pistol and get another couple kills.
Now i wanna play but can't.. Long work night =(