I am just going to say that I THINK that RAWR is a BAD sim to use for a DK when talking about stat values.
Also, there is a good reason why Aldrianas and Tosks are BIS items even tho they have AGILITY as the main stat in them.
Some agility items are better than strength items, by a lot.
Strength is not good because of Ravenous Dead alone, and I doubt 3% from Ravenous Dead makes any difference in the two specs, when it comes to stat prio on Strength, both specs have Unbreakable Armor that increases strength by 20% and 15% increase from the weapon enchant.
Even tho this is taken from UNHOLY GUIDE:
http://forum.warmane.com/showthread.php?t=326654
It is a perfectly reasonable explanation for Frost as well, on why Blood Sub-spec might be better early game:
"[Blood Sub-spec Without Reaping] 17/0/54
The most optimal single target build when poorly geared (which, in this context, is anything before 4P T9). The primary reason this spec is best at lower gear levels is due to Bladed Armor and Dark Conviction. Bladed Armor hardly scales since armor values on dps hardly scales, and thus gives a near-constant amount of AP regardless of gear level, making it a strong talent at the start, but relatively weaker as gear goes by. Dark Conviction provides a flat amount of crit, and crit gets weaker the more of it you have (i.e, 50 -> 55% crit is a smaller dps increase than 30 -> 35% crit). Once you get to 4P T9 and beyond, the two alternative specs will easily pull ahead, largely thanks to the failings of these two talents. Your auto-attack will be the highest percent of your total damage, followed by your Scourge Strike and then your Ghoul. Scourge Strike will be your hardest hitting individual ability, followed distantly by the combination of Death Coil and Unholy Blight."
Also, Strength items might be more valuable due to more Armor, that gets converted in even more attack power, when using Blood Sub-spec.