Ah, dunno what kind of teams you've met but for disc/rogue to go on shaman with 14k armor who actually gets to hit your priest, which any decent enhance/druid team would be able to, you're not going to win the mana war. Rogue does too litle on shielded enhance shaman and with half duration cripple and double cleansing, he's going to be shiving ALOT to keep him slowed, which further reduces damage. Include cyclone on rogue and entangle if priest runs too far, or cyclone on priest when he gets too far away from the shaman and shaman WILL be on the priest if they put their mind to it.
And any double dps team with rogue is easy for enhance/druid simply because double poison cleanse will allow for alot of full healing received and shadowpriest wont live long if they leave the shaman alone, same with warlock.
But guess you're going to have to try your way forward. Seems you people met alot of retarded druid/enhance though.
When you pick a tactic to run against a comp you shouldn't include the fact that they might be retarded and you might get a free win going for the wrong target, even if it may work against some of the teams. You should look at both teams full capabilities and assume they both play as good as they are allowed by their class, and play the game accordingly. If you then find out they are retarded, you will have an easy win either way you play it.
Out of personal experience, having 480 resilience in shield (with relic resilience shock proc) and 14k armor and 10% block if I turn to target, I've found tanking melees are one of the easier tasks in arena as enhance, and my druid has no problem whatsoever keeping me up against warriors or rogues, or double dps for that matter. They HAVE to switch for my druid or they will lose with 100% probability.
I find it amusing you talk about expecting both teams to be playing at full capability but you fail to mention that the priest actually may be doing something besides standing there and that the rogue might be doing something besides auto swinging.
The priest WILL be running at your druid attempting to fear and mana burn him, so i dont see him getting a ton of cyclone/roots on either players of the other team + the fact that roots can be dispelled and i hope the rogue has the druid on focus to cloak a key cyclone. Like i said, both slowing effects a shaman can use are able to be dispelled and are on a cooldown. Mixed with the fact that if he frost shocks, now he cant earth shock for 6 seconds. You say a shaman will be spamming tremor if the druid gets feared, but there are a couple things called communication and timing. like kidney shotting when the priest gets a fear?
I have a shaman with full venge/brutal for enhancement and even when i throw up a shield you aren't invincible or anything you still take in a good amount of damage. With the little amount of control you have on the priest he is going to be throwing up shadow word pains and they can even drag you behind a pillar and mind blast you. You say it's hard to keep the shaman off of your priest, but it really isn't there is kidney shot and the constant proccing of crippling poison. Sure you may dispel it but in the second or so that you are waiting for that to happen the priest could get around a corner and you could get kidney shotted.
Also a priest should be killing these totems unless they are retarded and enhancement shaman don't have a ton of mana. Yes they have water shield, but if they are spamming these totems and purge they can still get low.