I've rolled a tank and have picked up most experience in pvp (FUNTASTIC). Bad play overall but this was because my friends levelled way quicker than I and I was 10 lvls lower than them in flashpoints. I had no tank effect haha ... So now I'm very apprehensive about tanking flashpoints due to inexperience and the blame game to come.
The one thing I have to say (based on most MMO experiences I've had) is that somebody has to take control of the group and it's usually the tank. I swear I've seen scared little toons patiently hanging around tanks with tears in their eyes waiting for a speech. So, if you're poor at giving direction and there's no other, your group will more than likely fail.
At the moment I'm hunting for a good Sith Warrior tanking guide to flashpoint bosses and stuff ... any suggestions? Sorry, I tend to ramble.