This problem hasn't gone unnoticed by the playerbase. I myself pointed out the flaw numerous times during beta, yet nothing was ever changed. The players realize that this problem exists; Blizzard, too, must obviously see what is right in front of it. Why then is nothing done about it?
The simple answer is that there just are not that many alternatives. Commonly, it is suggested that mastery should be changed to alter the flow of Eclipse instead of altering the degree of Eclipse. I agree with this matter in principle, but the sad reality is that it simply isn't possible.
As I've said, Eclipse functions on a set of base numbers. For example, going from a Lunar Eclipse to a Solar Eclipse will always take 10 Starfire casts. There simply is no smooth way to alter this formula and keep mastery as a relevant stat on gear.
Usually, the suggestion is that mastery should change how much Eclipse is generated by each spell while outside of Eclipse. This holds absolutely no reasonable impact on Eclipse generation and wouldn't actually solve any issues at all. Say that you have each point of mastery increase Eclipse gains by 1 per spell cast. Okay, you now generate 21 Eclipse per Starfire cast instead of 20. It would still take 5 casts to reach the next proc. Mastery then would only actually do anything when you reach various factors of 100, such as 25. At that point, you lose a single Starfire cast off each rotation.
Now, there are variables thrown in through Starsurge usage, Euphoria procs, and Shooting Stars procs, but the basic premise remains. Only highly specific values of mastery would matter, and everything else would be meaningless.
The other alternative to this would be to similar reduce Eclipse gains while the proc is active, effectively extending Eclipse. While tweaking numbers could allow for additional factors of mastery to be more useful, inevitably the entire system itself would have to be changed in order to accommodate this. Even then, it wouldn't actually fix the issue that people are hoping for.
If you are going to have it both ways -- reduce Eclipse gains while the buff is active, and increase Eclipse gains while it is inactive -- then Eclipse generation overall would have to be rebalanced.
Consider this: Even going off a system in which every two points of mastery reduces the Eclipse gained while the buff is active by one, at 26 mastery you would only lose any Eclipse power via Starsurge at a rate of two per cast, meaning you would have to cast Starsurge 50 times in order to lose Solar. Hit 30 mastery, and you would never fall out of a Solar Eclipse.
Well, the obvious solution would be to put an artificial cap so that you always generate a certain amount of Eclipse, but this doesn't fix the problem. Once you create such a cap, the goal would then become to gear to this cap and then avoid mastery entirely, as it wouldn't hold any value beyond that point. Mastery would just become another hit cap that we'd juggle.
You could certainly place the cap at some absurdly high number that would never be reached, but, again, it wouldn't fix the issues that people are having now. In order to do this, you would have to create a system wherein Eclipse generation is absolutely horrid at low-level mastery, which would only hurt balance druids in the present to account for future stacking.
There simply isn't any method in which you could tweak the numbers where everyone is happy, and in the end, nothing is actually solved.
Now, the other solution that has been brought forth is to split the damage component of the mastery effect between both the Eclipse and non-Eclipse state. This is perhaps the only method that I have seen which would be capable of working. The changes to mastery in 4.0.6 actually make this a whole lot easier.
In this situation, mastery would give a certain amount of a damage increase to the Eclipse buff as well as increase our damage while not in Eclipse, which would require implementing an entirely new buff that is activated while not in Eclipse.
Given that our mastery currently increased the Eclipse bonus by two per point, this makes splitting the bonus rather simple. Merely cut it in half and spread it out over both situations; each point of mastery would then increase Eclipse damage by 1% and non-Eclipse damage by 1%. Simple.
In truth, real balancing would be slightly more complex than that. Although Eclipse uptime is a normalized function based upon number of spells cast, there are still other factors that need to be considered. To start with, Eclipse has a much higher uptime than 50% even on standard, Patchwerk-style encounters. This is due to various factors such as spells that benefit from Eclipse but don't generate Eclipse and Euphoria procs. Movement is also another factor that will impact Eclipse uptime in normal encounters, as would things such as DoTting multiple targets.
Due to these factors, you couldn't split the current mastery benefit right down the middle and call it a day. Instead, you would have to normalize it against estimated Eclipse uptime values. Eclipse's uptime varies from encounter to encounter and druid to druid, but the best normalization factor would be to do a 75/50 split.
Essentially, this draws the Eclipse bonus from mastery back to pre-4.0.6 values of 1.5% per point, while the druid would now gain 1% additional damage when not in Eclipse. While how this would impact balance would vary from encounter to encounter, the net change should equalize out or perhaps provide a small increase in damage.
Overall, our AoE/multi-DoTting potential would be reduced, given that we often sit in Eclipse during these times; however, our single-target damage would actually increase slightly because Eclipse usually has slightly lower than 75% uptime following the basic rotation.
In general, this would actually be a highly beneficial change to the game overall. In a vast majority of parses, balance druid do not generally rank highly on pure single-target encounters, yet we usually dominate AoE-based encounters that benefit from our multi-DoTting. This is a generalization and not an absolute truth. I know of a number of balance druids who can and have rocked the DPS charts on encounters such a Chimaeron, which is purely single-target. Our single-target damage isn't weak by any means, but there is just as much luck as there is skill involved in pulling out chart-topping numbers in these situations. Due to how much stronger we are during Eclipse, certain procs and effects are much more potent when they align in specific ways.
For example, blowing a potion, haste trinket, and Berserking while under Bloodlust and a Lunar Eclipse so that you are able to easily push to a Solar Eclipse while Insect Swarm and an Eclipsed Moonfire so that they get the full benefit of the four-piece T11 bonus is going to yield a higher DPS increase than doing so during a Solar Eclipse, when you'll end up breaking the GCD. Having Starfall's cooldown perfectly align with the middle of a Lunar Eclipse proc will yield more DPS than having it come up just before a Lunar Eclipse proc.
Some of these variables are controllable; some are not. You can try to time Starfall for a Lunar Eclipse all you want, but Euphoria and Shooting Stars procs, as well as haste procs, are going to alter any planning that you had.
That all aside, this change would most efficiently address more of the issues in the best way possible. It would increase our single-target damage in a more controlled method, it would slightly reduce our AoE potential, and it would make us less worthless outside of Eclipse procs. All in all, it would be win-win.
Make sure you tune in next week as we continue to delve into the world of Eclipse!
Every week, Shifting Perspectives: Balance brings you druidic truth, beauty and insight ... from a moonkin's perspective. We'll help you level your brand new balance druid, tweak your UI and your endgame gear, analyze balance racials and abilities, and even walk you through PvP as a balance druid.