It's not hard to understand that dk mechanics are outdated right now, just compare some of our abilities to other classes and amount of cc they got in mop and maybe you get the picture.
Direct quote from Anotherx, winner of the European World of Warcraft Invitational 2012.
Our resource system cannot keep up with the current state of the game, our main damage ability requires 2 runes, which is all fine and dandy for pve, but once you have to use a rune outside of "pve rotation" it causes hassles and leaves you sitting on unholy runes with no worth while means of getting rid of them.
Necrotic Strike costing a death rune - It's currently not worth using necrotic strike other than the debuff and even then it's debatable. The absorb it puts on is so minuscule the riptide, rejuv, holy shock etc. will have removed it before you can use another ability. Obliterate will be 99% of the time the better choice to use in conjunction with a death rune.
Dk's are by far the easiest melee to shut down. Warriors charge every 12s and have a 3minute cd making them immune to movement impairing effects, feral's can shift all snares and roots while moving at an increased speed and ret's have the ability to dispel themselves, again while moving at an increased speed.
However when it comes to dk's we have deathgrip every 25seconds, which by most classes by the time they land give it 1 or 2 seconds they're out of range already. As frost we're forced to play in frost presence making us the slowest moving melee, frost presence needs to give the same movement speed bonus as unholy presence and death's advance needs to go back to being baseline, the current tier death's advance is in it's an impossible choice to pick it.
DK's have no utility, we have no cc at all, in the current state of mop every other class has 10 of them. Warriors aoe fear 1min cd and a 20second aoe stun, Ferals every 5cp's instant cyclone or root. Ret's can get a 30s cd stun, and the most stupid of all abilities Blinding Light. Yes lets remove hungering cold because an instant aoe unavoidable cc is much too overpowered. Then turn around give the ability a new name and give it to ret's, good joke!
What do dk's have in the way of cc? The only choice is Remorseless winter, which is a stun that takes 5 seconds to actually stun, if it was instant and aoe sure it would be amazing. However in it's current state every class can counter it, druids can shift out of the snare, freedom completely negates it, other dk's can ams it and the list goes on.
Then onto our silence. Strangulate is the worst silence in the game. It's on gcd, no other silence is, it's a 2min cd the longest of all silences, and it costs a blood rune. With the removal of blood tap, it's pathetic, you have to either be lucky enough that when the situation to strang arises you happen to have a death rune, or you have to sit on your rune twiddling your thumbs.
We need death's advance basline.
Revert necrotic back to 1 unholy rune, remove the casting speed debuff.
Make Strang 1min cd, off gcd and no rune cost.
Put hungering cold back in the game on a 2minute cd, it's no different to blinding light, or make remorseless winter instant.
Best of All buff unholy so we don't have to play frost.