In the world of warcraft, Rogues have lots of tools that can help them gain honor fast and the ability to turn the tides of most battles just by using a few areas of their class. Whether you want to be "greedy" and pick off people in battlegrounds by yourself, team up with another Rogue to capture points on the map, or aid your team in a massive battle; the Rogue can excel in any one of these areas.
Some people don't like dagger builds because they say they are weak and even more don't like subtlety/shadow-step builds. It may be true, that the build is less superior in Arena or when Dueling 1v1 or any other type of equal ground battle, but in battlegrounds these conditions do not exist; therefore, using Daggers/Ambush/Shadow-step is a very viable build if your goal is to farm honor and have the biggest impact in the shortest amount of combat time. Your burst damage will be too great.
Others are not going to disagree with this but the fact is you don't get a amount of time to sit there and stunlock someone in a battleground unless you are off soloing by yourself or defending a tower. It doesn't matter if you ambush, sinister strike, backstab, or just auto attack you're crits and damage are going to be reduced either way, it's not like ambush is disproportionately reduced in comparison with other attacks and we are talking about farming battlegrounds here, not Arena or Dueling.
From time to time, you will see Rogues guarding or taking over towers, they do well in it because they have sap/gouge/stunlocks or just a load of damage. It makes it extremely hard for anyone to go 1v1 into a tower and sometimes 2v1 and beat a Rogue or take the tower over. With Dirty Tricks talent you don't even have to be close to blind or sap them and with camouflage you move extremely fast in stealth so it is less likely you will be found. Start your defense at the bottom when you see someone coming and sap them up the tower all the way, remember it has a diminishing effect, but you can just go ahead and gouge or cheap wow gold shot them and vanish or walk away or wait for them to try to cap the flag and do all of these things so you interrupt them.
Picking off low health players or killing casters is what you should be doing in battlegrounds. If you want to run into the center and fight melee classes with your super awesome sword/mace combat, go reroll a Warrior and quit wrecking the potential of the class. You can't afford to let low health targets (that someone else put time and effort into attacking) run to the back of the battle only to stand there and be 100% effective casting or shooting people. You also shouldn't let them run away to heal themselves and come back. As a Rogue you should be stealthed behind big battles or shadow-stepping across them to pick off the low health targets, this is the best way to benefit your team. You can also ambush or distract full health healers which will further aid your team. Sit right at the back of a big battle and just hit tab and wait for a low health target to show up, ambush/kill them, walk away or vanish and come back and do it again. It is one of the best things you can do to help win in battlegrounds.