Why do most Subtlety Rogues in WOTLK use Attack Power instead of Agility?

I’ve been digging into stat choices for WOTLK Subtlety Rogues and noticed something interesting.

If we look at other classes/specs, their main stat is always the one that scales their damage the best:
• Warriors, Ret Paladins, Unholy DKs → Strength
• Hunters, Feral Druids → Agility

But when it comes to Subtlety Rogues, most of them seem to prefer Attack Power (AP) gems/enchants over Agility, even though Subtlety has the talent Sinister Calling, which gives a big bonus to Agility. On paper, you’d think Agility should be the go-to stat for Sub Rogues.

So my question is: why is AP prioritized over Agility for Subtlety in WOTLK?
Is it because of scaling issues with crit from Agility, diminishing returns, or the way Subtlety’s core abilities (like Backstab and Hemorrhage) benefit more directly from flat AP? Or is it simply that Subtlety’s scaling with Agility is weaker compared to other specs, so stacking raw AP gives better DPS overall?

Would love to hear from people who played high-end Sub in bgs/arenas — what’s the reason behind AP being better than Agi here?

1. Hit Rating
2. Resilience
3. Attack Power

Attack Power directly increases the damage dealt by your attacks and skills. It scales slightly higher than pure Agility as Subtlety, especially since the value of Crit is slightly reduced by the enemies Resilience.
4. Agility


Dumbass Nevermore from Tavern says -

Stat Priority
Hit Rating
Expertise
Resilience
Armor Penetration
Attack Power
Agility
Critical Strike Chance


Qubro says -

AP, ARP or AGI ? ÔÇô This is very highly debated issue. As a subtlety rogue you should have 2 sets for PvP. One with attack power stack and another with ARP stack. Of course, ARP is more useful against platers and attack power more useful against cloth enemies. With your ARP stacking , It's important that you have atleast 40% arp. Best is 50%. I know 50% is kidna hard to get without pve items and keep resilience up to 950. But It's not imbpossible. You can do some pve. Actually, there is a lot of PvE items for ARP, and they are good, but there are difficulties that arise with resilience and arp. So, my tip is, you don't need to stack only ARP in your sockets. You can use few others like 20 resilience. Anyway, you have to think and speculate about your gear and try to balance it. Also if you roll AP stacking, best option is to have some arp pve parts with full attack power stack.

I also tried AGI stacking. Don't do that. It's good for crit and dodge, so you can be little bit more defensive against other melee classes and also have some more critical hits but nothing else. Probably choose between AP or ARP. Or both with 2 sets.

well, pretty simple.
Your talents already increase by a lot your crit chance.
1 talent give +50% crit chance on ambush
1 talent give +30% crit chance on backstab
(and these are the main spell when you are going for a kill)

Thay is why you can focus more on AP or Arp.
Your chance to CRIT is almost guaranteed anyway

wrong. arp stacking is better vs cloth. you'd do more damage stacking ap vs plate. Source? Homerjay's work