So I've notice this bug... Or I'm not sure if its a bug. But healing values inside and outside BGs are not the same.
I first noticed it on my Hpala. I crit flash of lights for about 12.2k outside of BGs but inside BGs it only crits 9.5k.
So I've decided to take a few screenshots of my druid's heals. Normally its Rejuvenation ticks for 3k outside BGs but inside BGs it ticks for only 2.7k Also Nourish crits 12.5k outside BGs and only 10k in BGs.
I would just like people to try and confirm this before I try and put it on Bugtracker.
All screenshots were taken with the exact same buffs. No extra trinket procs etc. are active in order to heal at the same bonus healing power.
It's not a bug, it's the Wotlk equivalent of battle fatigue which I'm too lazy to dig up but it's about 10% less healing overall in instanced PvP. Go home.