Playing defensive in the arena often gets you nowhere, as without pressure being applied on them, the opposing team is essentially free to do whatever they want, especially gaining better positioning or a stronger mana pool. This was the case yesterday in a long and incredibly stupid match against a War/Sham team that practically copulated with the pillars in Nagrand. With no pressure against me, and with both opponents doing the Maypole dance, I was able to keep my mana pool high and essentially heal them to death.
Now, the case for defensive play can often be the right call, but it shouldn't ever be the focus as a means to win a fight (nor should draining mana). It should be used to stabilize a bad situation or put your team into a better position to go on the offensive.
I've downloaded quite a number of WoW PvP arena videos, and one of the best displays of defensive play is from a recording from the recent North American Regional Finals. This match was Warrior/Warlock/Druid (Rhaegyn/Glickz/Hafu) vs Resto Shaman/Shadow Priest/UA Warlock (Kollektiv, Offcell, Mazud), aka Shadowplay comp. On paper, the combined might of offensive/defensive dispels, Bloodlust, and two sets of dots in addition to the dreaded silence/spell lock combo heavily favors Shadowplay.
So how did WLD win an unfavorable match up?
At the start of the second match, on the Nagrand map, Glickz (Warlock) was the only player from WLD to step forward into the open area. None of the Shadowplay team members ventured far from the safety of their pillar and for a good minute or so, it was a bunch of dot trading on both sides. Throughout all of this, Rhaegyn (Warrior) stayed mounted behind a pillar as the Shadowplay team moved as a team to dot him up.
author's note: The Warrior is the prime target for caster teams as he has no way of self healing, takes extra damage when in Berserker Stance and must get into melee to apply pressure. The Warlock is a bad second target as Fel Armor, Soul Link, Siphon Life, high resilience and a high HP pool make the Warlock a very difficult kill target.
This sort of defensive play by Rhaegyn forced the Shadowplay team to overextend their positioning, allowing the felhunter pet to be killed (by Rhaegyn from behind a pillar, no less) and putting the Offcell (Shadow Priest) in a bad position, which lead to a kill during in a nice cc chain from Glickz and Hafu.
To get to that point, the dots from Glickz forced the Shadowplay team to move closer to their opponents' side of the map. As the match went on, Offcell was forced to spend mana, effectively limiting the match duration due to mana issues. Furthermore, Rhaegyn's play of not exposing himself to the Shadow Priest and Warlock dots until his need for healing wasn't a liability meant that Hafu only had to concern herself with healing two people instead of three while avoiding fears. This was quite reasonable, especially with Glickz LOSing the opposing DPS to get a new set of hots before heading back out. With the effective use of defensive play, Hafu and team effectively neutralized Shadowplay's advantages and clinched a decisive win.
So, if your team is just not in control of the situation, consider playing a little D until you get an opening to turn the tides.