One of the other solutions is to just increase the cast time of Wrath. PvP ramifications of this change aside, let's take a look at how this would function. In order to make such a change, it must not upset the current balance that we see between Wrath and Starfire's DPS. Although one will always deal more damage than the other (and in this case, Wrath will most certainly be the higher DPS spell), so long as there is a note of parity between the two spells, we are fine. Conceptually easy, making a change of this scope isn't all that trivial. Changing a spell's cast time impacts scaling in so many different ways, mostly from haste and spellpower; however, proc effects are also impacted.
First things being first, the base damage of the spell has to be readjusted to ensure that it remains close to the same value. Wrath currently has an average base damage of 592, for a base DPS value of 395. In order to get 395 DPS, the average damage of Wrath needs to be increased to 790. Wrath currently has a damage range of 70 between the high end and the low end. Having a damage range of 770 low end and 840 high end would yield an average damage of 795, which is workable.
Next comes spellpower scaling. Currently Wrath, once talented with Wrath of Cenarius, gains 44.76% spellpower per second. By increasing the cast time by .5 seconds, the base coefficient is increased to 71.42%, which would be increased to 81.42% by WoC. This would yield 40.71% spellpower per second. There probably don't have to be any adjustments made to the spellpower coefficient at this point. Although Wrath would lose some spellpower scaling, it would still have higher scaling than Starfire, which gains 40% spellpower per second. If the spellpower scaling is too low, then increasing Wrath of Cenarius to 15% for Wrath would yield 43.21% spellpower per second. There isn't a factor of 5, which would set it to 44.76%, and Blizzard seems to like those factors, so this is probably the closest you could get.
Next comes the theoretical testing to ensure that the paltry difference in damage that we want still exists. To do this, you need to use at least two different testing points: a low-end gearing point and a high-end gearing point. For the high end, we'll use this gear set-up and adjust the spellpower by 1,500 and the crit by 5% to account for raid buffs. Although it isn't really the low end, which would technically be Naxx level gearing, we'll use this gear set-up but not adjust any of the stats to try and get it closer to the level we want. For the sake of clutter, I won't list the actual calculations, just the results. The 2-second Wrath will use the 81.42% coefficient to start with.
1.5 Wrath -- 7,842 DPS
2 Wrath -- 8,040 DPS
Starfire -- 7,650 DPS
1.5 Wrath -- 4,298 DPS
2 Wrath -- 4,088 DPS
Starfire -- 3,889 DPS
This data shows a sketch, but not the whole picture. All of these calculations were done using the current Nature's Grace mechanics, which do not favor the 1.5-second Wrath at all, and it is the sole reason why you see the gap between the 1.5-second Wrath and Starfire close as gear increases. It is also the reason why you see the 2-second Wrath scale up far beyond both of them. If you remove Nature's Grace from the equation, changing Wrath to a 2-second cast time is actually a nerf to the damage of Wrath, with the 1.5 cast time yielding 7,439 DPS and the 2-second cast yielding 6,884 (Starfire also takes a major scaling hit dropping down to 6,668 DPS). That is to be expected, though. Remember that the coefficient for Wrath is actually decreased by adjusting the cast time higher. The superior scaling from Nature's Grace masks this flaw by allowing the 2-second Wrath to actually outscale the 1.5 second version. However, without Nature's Grace impacting scaling, the 2-second Wrath and Starfire are fairly close to each other in terms of DPS, which is what we want.
Nature's Grace as it currently stands is terrible for Wrath's damage, yet it is actually a necessary evil in some respects. Without Nature's Grace there to act as a cap to Wrath, then Wrath is able to far out-scale the damage capacity of Starfire; this is mostly due to the superior spellpower scaling of Wrath. As much as we want Nature's Grace to be removed, the data suggests that it actually has to stay in the game in order for the damage parity between our spells to function properly. In order to remove Nature's Grace, Wrath needs to either have its cast time increased or a talent has to be introduced with the specific intent of boosting Starfire's damage. It's a form of catch 22. Without removing Nature's Grace, increasing Wrath's cast time to 2 seconds causes the spell to outscale Starfire, yet removing just Nature's Grace still causes Wrath to outscale Starfire.
When Ghostcrawler said, "messing with a talent like Nature's Grace for 3.3 would be very risky in terms of nerfing Balance or causing other unpredictable side-effects," this is what he was referring to. The damage capacity of Nature's Grace is fairly trivial to account for, but the impact it has on scaling, particularly Wrath's scaling, is a different issue. We simply cannot remove Nature's Grace and call it a day; parity must exist with Wrath and Starfire's damage in order for the rotation that Blizzard wants us to use to work. Given that, even without Nature's Grace Wrath can still have GCD clipping issues in certain situations, it would probably be for the best to make both changes in tandem with each other; remove Nature's Grace and increase Wrath's cast time by .5 seconds.
Attempting to balance out a 1.5-second spell and a 3-second spell when there is such a vast scaling disparity between to two is becoming very problematic. What works for one generally doesn't work the same way for the other. Nature's Grace shows this; so too does Wrath of Cenarius and Starlight Wrath. Changes need to be made to the core of the balance druid's spells, and this is one change that I really would like to see make it into the game. I would miss machine gun Wraths just like everyone else, but game balance has to take precedence over that.
Every week, Shifting Perspectives treks across Azeroth in pursuit of truth, beauty and insight concerning the druid class. Sometimes it finds the latter, or something good enough for government work. Whether you're a bear, cat, moonkin, tree or stuck in caster form, we've got the skinny on druid changes in patch 3.3, a look at the disappearance of the bear tank, and thoughts on why you should be playing the class (or why not).