This battleground is the bread and butter of each team and has been around the longest in the wow history. It is a simple capture the flag battleground and lasts 20 or untill someone has captured 3 flags. Most competitive games will last the full 20 minutes, unless someone manages to capture 2 flags, in which case its GG 90% of the time. In the start of the game you want 9 out of 10 people to leave the gates trough your graveyard. The 10th will go trough the tunnel and pickup the speed buff, so that the enemy FC can't get it if he manages to push trough you (which will happen 90% of the time), this should also be the person picking up berserking, usually a warlock or balance druid.
You should have 9 people fairly close to eachother and your FC on the right side of the map, so he can slip trough as soon as the fighting starts. DONOT have your FC try and get the flag before the midfield fight has started because otherwise they might turn around and try to kill him, if they succeed they have a huge advantage and even if they fail they force you into a bad position (fighting close to their base, near their GY). If they have a mage, rogue, hunter or sometimes even balance druid, chances are they will try to slow down your FC to prevent him from getting to the flag, anticipate this by having a player (preferably a dps who can heal and peel well, like a spriest or a balance druid) be mounted up untill all of the aforementioned classes are either in combat or trying to engage the tank, if they try to engage the tank it's his job to cc them/slow them down so the tank can run past safely. Thanks in this case should never dismount unless absolutely nescesary. Ofcourse if you are using a feral druid as FC, you shouldn't have to worry about it, since he should just be stealthing past them. Personally I dont try to go for the enemy FC because im not using a hunter or rogue and am fairly confident in my groups ability to wipe the enemy team midfield. However if you have a feral druid and they have a warrior, it might be worth sending 1-2 people back to try and catch the EFC and get a quick cap.
90% of the time the fight will start when a DK gets a decent grip going and people connect on that target, if you donot have a DK, make sure you engage them first because if they grip you you are in a bad shape
While struggling in the mid try and wipe them one by one, follow your targetcallers orders and hope your team is good enough to wipe them. Try killing them and pushing them back to their graveyard. If you get close to their graveyard quickly, stop advancing and just keep them boxed in, make sure nobody escapes, that way, when their FC enters midfield, you can easily swap onto him and kill him.
By now, both FC's should have the flag and should be running back, if you are wiping them your FC should take the tunnel, if they are wiping you you should all disengage and meet up with your FC at the ramp to get him across the map safely.
If you see their FC come out of your tunnel and you are on their side call for a disengage of 2-3 people (preferably high-burst classes, like mages spriests and destro locks), everybody else should stay fighting and slowing down the enemy team while those people go for the EFC. This will usually force 1-2 major cooldowns (last stand/shieldwall) out of their tank or even kill him allowing you to get an easy cap.
If this doesn't happen, have your FC stay behind the group, and have an Hpaladin keep an eye on him, if they want to swap onto your FC they should either use a grip (which can be countered by life-grip) or charge trough your full group, which leaves them and their healers exposed allowing for a quick wipe.
Once you start pushing them towards their graveyard, send your FC together with 1 hpaladin back to your base and start pushing for their FC. Keep an eye on their spawntimers and try to kill some of them while the rest just spawned for an easy second wipe. A good way to do this is have a stopwatch set to 45 seconds and push it every time they ress (if one of you addon people read this please help me and make this for me) With 3 stacks up a Deathgrip-Stun-Smokebomb (if with rogue) should force major cooldowns/get you a kill. If the EFC isn't standing at their GY but rather in their base, you need to wipe them one last time (should be easy since they will most likely have a healer with their FC) and then have 2-3 people go for the EFC, against heavy burst classes like lock/spriest/mage are ideal for this (though mages not so much after the recent frostbomb nerf).
If you don't have the group to wipe them and they are pushing you back, the only way to win is to fight on your graveyard, with your FC behind you or even on top of your graveyard (warriors can intervene up and (s)priests can grip healers up. Keep in mind that they can be gripped down by DK's and that warriors/rogues can shadowstep/charge up the graveyard aswell. If you can't even wipe them while standing on your own graveyard, your in trouble, bigtime. The only way you can win now is hoping that you cán beat them 5v5. What you do is split your group up and go to roof, group 1 will be defending, group 2 will be attacking. Group 1 should consist of the FC, 2 healers and 2 dps who can slow/knockback/control enemy attackers well, like mages, balance druids, warlocks or dk's. Group 2 should consist of 1 healer and the other 4 dps, and should be going for the EFC (if you let them into your base, their EFC will go back to their base which leaves him vulnerable). From there on its your job to win the 2 fights, the best way of doing this is having the warrior stand on your roof and have the balance or resto druid regularly knock them down into your flag room, which causes them to have to waste time running back up again, which gives your offense team time to kill the EFC. Alternatively, if you have a really good feral druid, you can try the kiting strategy, if you do this well you can keep running endless laps around your base and not get caught, remember to only do this with a good feral druid since he will LoS/range your healers aswell and if he gets caught while the healers arn't there he will die very quickly. Remember that after 4 stacks travelform doesn't give any speed boost anymore, so the only way you can kite is by being in bear. Make sure that if your attack team thinks they can kill the EFC soon, that your FC gets ready to jump off the roof/run into the flag room to prepare to cap. Rinse and repeat this strategy for profit
If you are ahead 1 flag/capped last and its almost time, you can consider camping your roof, this is a pretty risky strategy but it can pay off very well. Donot consider camping unless there is less then 10 minutes left when the flags are first picked up. The way to camping is having your melee stand below the ramp, ranged stand up the ramp and FC stand near the edge of the roof, that way, if they want to reach your FC, they will have to go trough your entire team before reaching him.
Also make sure to utilize knockbacks on roof to the fullest extend, knocking 3 dps off while their rogue is bombing is priceless.