I heavily participated in the closed beta over New Year's weekend and leveled from 63 to 66 using a two handed weapon. During this time I killed an awful lot of mobs and it occured to me that I had never seen a double Windfury alpha strike-- that is, to have Windfury proc off both my normal attack and off of Stormstrike at the start of combat. This prompted a good deal of further testing, and I have come to the conclusion that Windfury Weapon proccing invokes a hidden three second cooldown during which time that weapon buff may not proc again (that is to say, each hand has its own cooldown when dual wielding with double WF buffs).
The existence of this cooldown was confirmed during testing on the Live server against the invincible Servants in the Blasted Lands. Over the course of 20 minutes using a 1.3 speed Julie's Dagger, I had zero back-to-back procs of Windfury and in fact did not have any occurances of proc-hit-proc, all procs were at least two swings apart. I had two further ten minute tests using a 1.8 and a 2.7 speed weapon and again I had zero back to back procs, but this time I saw proc-hit-proc. When using any two handed weapon (I have none under 3.0 speed) I was able to see consecutive Windfury procs. For this reason I believe the cooldown is three seconds, and since posting my initial findings several other shamans have parsed their logs and they support this conclusion. If you are skeptical I would encourage you to run your own tests, I am certain they will confirm these findings.
There are many people who would say that ten minutes is not a very long parse for some tests but the odds of a Windfury proc directly following an already-seen proc is 20%, just like how your odds of any coin flip coming up heads are 50% no matter the result of the previous flip. Ten minutes is more than enough time to have seen consecutive procs.
At one time Windfury could proc off of itself so this is definitely a change that has been made since the game's release. This cooldown was possibly introduced with the changes to Stormstrike to avoid shamans being able to double-windfury proc at the start of a fight and instantly kill a PVP opponent. Doing this should really be quite easy; with sufficient AP and a slow two-hander a round of 5000 or more damage basically instantly is more than possible. This is certainly a valid concern given the recent trend of moving away from PVP one-shotting in general. (Contrary to what many people people believe, Stormstrike is not normalized and does proc Windfury. I believe the reason this belief arose is due to this cooldown: SS would never cause a double proc of Windfury and so people simply believed that WF no longer procced off of a SS hit. This was proven to me when I was knocked down and stood back up and my normal attack was parried and my SS attack hit and I had a Windfury proc.)
However, this cooldown is not tied to our weapon speed. Whether you are swinging a 1.3 speed dagger or a 3.9 axe, you have to wait 3 seconds between Windfury procs. More parsing has shown that the overall proc rate of Windfury is lower than 20% with a one-handed weapon, and the proc rate drops off as you get progressively faster weapons. I wrote a program to simulate sustained melee (
http://www.noobschoolbus.com/wow/wftester.cs) and tracked the actual proc rate across large combat samples (50,000 seconds repeated 3 times). When there was 0 cooldown on Windfury all results were within 1% of the expected 20% so the accuracy of this program is fairly high. Additionally this test was run with the belief that each hand has its own cooldown, this has since proven to not be the case and so results will be worse than what is posted here.
Single 3.8: 18.0%, 17.9%, 17.9%
Single 3.4: 17.8%, 17.4%, 17.8%
Dual 2.9: 17.7%, 17.7%, 18.1%
Dual 1.8: 16.4%, 16.5%, 16.5%
Dual 1.4: 15.77%, 15.85%, 15.80%
2.9/1.8: 17.13%, 17.15%, 17.08%
Since Windfury is an approximate improvement of autoattack damage by 40-45% depending on AP, losing up to 5% of your Windfury proc rate means you are giving up approximately 10% of your damage. This effect is exaggerated against higher level mobs becuase of Windfury's innate power to avoid glancing blows.
The obvious solution is to use weapons that have close to a 3.0 delay. Therein lies the problem: all of the new Shaman abilities at the bottom of the Enhancement tree are geared towards using faster weapons. Unleashed Rage's duration is static, meaning that the more attacks you have in the span of 10 seconds the more likely it is that you will keep the buff up on yourself and your party. Using slow weapons that approach a 3.0 speed improves Stormstrike ever so slightly, but hampers the effectiveness of both of these arguably more-important abilities greatly. Furthermore with 5/5 Flurry, you need a 3.9 speed weapon (all but non-existant) to avoid having consecutive flurried attacks come less than 3 seconds apart. Effectively, a crit becomes somewhat detrimental because it prevents Windfury procs on consecutive swings which are considerable damage when using a slow two handed weapon. You trade 30% haste for a possible loss of 300% damage on that swing. For a similar reason using Stormstrike following a Windfury ensures that you will not proc Windfury off of your Stormstrike attack, which is already precious due to its long cooldown and three-fold effectiveness in improving Earth Shock's damage, fueling Flurry and Unleashed Rage, and to provide extra hits during Shamanistic rage.
Making effective use of UR and SR is now in direct opposition to maximizing actual DPS for more reasons than just improving your Stormstrike damage. Using Stormstrike is no longer about just adding more damage, it's about timing it to maximize your Windfury potential. Of course, this is a HUGE downside in PVP for fairly obvious reasons.
In essence: the Windfury cooldown is completely counter-intuitive to the playstyle of the Enhancement Shaman as suggested by the new talents.
I am not suggesting that this cooldown breaks our class, but there are very few shamans that would argue that Windfury is not a defining class feature and to have it inhibited in such a fashion that it no longer accurately reflects the tooltip and does not provide the gains it should is frustrating to say the least. I can understand the wishes of the developers to avoid instant kill fights in PVP, but there needs to be some sort of change made to this to perhaps tie it to weapon speed or to provide visual feedback of when the cooldown is or is not in effect. I would be very interested to know why the developers chose a 3 second cooldown for this ability.
While you are at it, changing Flametongue's +damage coefficient to scale with weapon speed (which reflects the changes to Seal of Righteousness) would be nice.