So... just by running over your stats, they seem rather low.

Not boasting or anything, but, it seems that your Health/Defense is lacking a bit.

When I was 77 with my DK team, I had 19K health without any outside buffs, and about the same defense, maybe a little more, but all my DK's never reached cap till Heroics.

Now, I know, you are running a different setup, but, hell, even with the STA buff you should be getting a lot more HP.

I don't see a problem with skill, just gear. Though, I did notice that you didn't kill both the Pawns before engaging the boss, so, that is a no no.