Class balance in PvP vs. PvE

Another readers' letter, this one I'm going to quote in its entire length. Except for the name at the end, because I only do that if I either have explicit permission, or the signed name is a pseudonym to start with.

Dear Tobold,

I am a regular reader of your blog. Had an idea recently, and I think that your blog is a much better place to discuss it rather than the cesspit that is the official forums.

It is regarding class balance. In my opinion, one of the main difficulty in balancing the classes is the need to balance for 2 very different situation, PvE and PvP. The mechanics are too different between the 2, thus balancing becomes much much harder. Just one example out of many, the priest SW:Death is meant to be a burst damage skill, of much more utility in PvP. However, many shadow priests are incorporating it into their raid dps spell cycles, ignoring the mirrored damage because VE will heal them sufficiently anyways over the cycle, thus boosting their dps significantly. This is not the intended nor anticipated use of SW:D. Hence, it was nerfed recently - the cooldown is doubled now.

What is the central difference between PvP and PvE mechanics? The answer of course is the existence of threat tables for the opponent you are fighting. The opponent's choice of whom to attack is constrained. Now what if both the opposing PvP team AND your own team are similarly constrained. If properly implemented, the situation of the fight will be quite similar, designated tanks try to force the opponent to attack them, allowing damage dealers to maximize their dps in peace, while the healers try to keep the tanks alive. However, the main implication is that PvPers cannot freely target whom they attack in a group fight situation. Now, people may argue the free-for-all of the current PvP is more fun etc. However, when I imagined PvPing under these rules, I see possibility of the fights becoming much more interesting and tactical than it is currently.

What is your opinion?

Good analysis of the problem, but I have doubts whether the solution will work. I could see how you could make a taunt ability work temporarily, forcing somebody to switch target. But forcing the whole opposing group to target the tank of your group isn't going to go down well with the PvP crowd. Where is the fun if you can't even make choices of who to target?

But I'd be interested to hear what you think of it. The discussion is open.