I know that this is VERY debatable(+spelling), but there is more to PvP than just Battlegroups.
-Dueling
-TGA
-Cross Faction FFA(Alliance vs Horde in random Areas)
It's easy to PvP without bgs, sure it's fun to pvp with bgs but you can definately PvP without doing BGs.
How Viable are DK's at 60? Imo Gem Stam and go blood spec:
Lets say roughly you get like... 10,000 Life( we all know you can get more but it makes the math easier to do)
[Death Strike] - 5% of your life is regained with one disease on your target. If you have two that will be 10%.
That will let you gain 1,000 Life with one death strike. Your able to cast two in a row, giving you 2,000 Life.
[Glyph of Rune Tap] - Adds an extra 10% to the life you gain.(Putting you at 20% Life regained instead of 10%, which is now 2,000 life) and also healing your teammates for 10% of their life[this is good for arena]
[Rune Tap] - 10% Of your life is instantly gained. If you have 10,000 life; you will gain 1,000 life.
[Improved Rune Tap] - Doubles the life you gain from Rune Tap. If you gain X Life, It will now be 2X( 1,000 life is now 2,000 life. If you have
[Glyph of Rune Tap] then it'll now be 4,000 life returned [if my math is correct]).
Then you throw in Blood Presence, Lifeward, and add Heroism trinket in there with bloodworms, and your healing will be none stop
of course if you have more than 10,000 life, your healing will increase with DS and RT.
- BUMMERS
1. Your burst damage won't be flying through the roof.
2. If someone does a healing reduced affect, you might find the fight harder ;/