Since the Beta of WotLK the “Taste for Blood” talent for Arms Warriors has been bugged. This has been known for quite some time, and bug reports have been made a plenty.
Here´s whats wrong.
Taste For Blood gives you a 100% chance on your Rend Tick to make you able to use Overpower.
This has an Internal 6 Second Cooldown, so naturally you should get access to Overpower every 2 Ticks(Rend Ticks every 3 seconds), disregardingg the first which is after 3 Seconds.
With Glyph of Rend your Rend is active for 21 Seconds so it should look like this.
Rend, 21,20,19,18(TfB OP procc),17,16,15,14,13,12(TfB OP procc),11,10,9,8,7,6(TfB OP procc),5,4,3,2,1,0(TfB OP procc)
So on 1 Rotation it should give you 4 Stacks aka Proccs, but here is where the Bug happens.
It looks like this very often:
Rend, 21,20,19,18(TfB OP procc),17,16,15,14,13,12,11,10,9(TfB OP procc),8,7,6,5,4,3(TfB OP procc),2,1,0
It basically does´t procc every 6 seconds like it should and is inconsistens and instead of 6 seconds gives you 9 seconds downtime.
This might be because the IDC and Rend Tick dmg do not allign Properly which is a BUG.
I have tested it extensivly and Haste can t be an issue since rend isn t buffed by it, so it might be server Tickrate.
Anyway, this does mean that Arms warrior will have a significant dps drop since Overpower is very important in the Rotation, I´d like to see it changed before the raiding starts since Arms isn t the best dps to begin with.