That does happen at first, but eventually you get used to following the herd. As long as you stay with your team you usually won't get ganged. If you feel you're getting gang, time to pop defenses and try to get behind your alliance and use them as a shield. Occasionally, your alliance does nothing to defend you, but usually it initimidates them enough to retreat.

The main time I run ahead as a tank is if I have Hallowed Ground up. I use this to act as bait and push ahead. It's shocking how well this works - just me, on my own, running ahead with Hallowed Ground makes the opposing teams flee in many cases and can motivate my team to then push.

Outside of that I just push ahead slightly with my team roughly by my side ish, maybe me just slightly ahead. That way I can retreat behind them if I'm being ganged, then stun any stragglers that chase so we gang them.

To be completely honest with you, the only thing I don't like in PvP is 1-shot attacks like Samurai has. It comes completely out of nowhere, when I'd otherwise be completely confident of surviving a one-on-one duel with someone, or even a 1vs2.