dike, you forgot the dodge from Unholy. The end result is something like
this. No Heart Strike, because otherwise you can't reach into Frigid Dreadplate and have Anticipation maxed. Death Rune Mastery is useless because Death Strike > 2x Blood Strike. People like this spec because it has the same healing as Blood, but it also has higher avoidance. Of course, I think that people are *****s and that breaking your spec, not taking Heart Strike, Morbidity etc., for the sake of 3% miss is ridiculous, but oh well...
DK is not a very hybrid-friendly class, that's all.