The WLK Hit Cap and the Cataclysm Hit Window

This is a brief explication of an issue that's been coming up more and more as we near Cataclysm, which is that people need to change their intuitive understanding of how to think about the hit cap and gear around it. The major change is the addition of Reforging.

The main focus of this post how you go about your quick mental evaluation of gear. Obviously if you're using a computational gear optimizer, it will spit out the right result regardless of how well you understand these points. But very often it helps to be able to form a good estimate of how useful an item is without giving it the full mathematical treatment. And here I describe the most important change to implement in your mental gear estimator from WLK to Cataclysm: you have to replace your prior understanding of the hit cap with a new one, which I here call the "hit window."

Discussion

A brief summary of how things worked in WLK:
1) Below the cap, hit was far stronger than other stats, and above it, hit was worthless.
2) The only ways you could change your hit rating were to change gear and change gems. The latter was a limited option, because except for any yellow sockets with good bonuses that you happened to have, you were trading away valuable Spellpower in order to regem.
3) The result is that you had to choose gear whose total innate rating was very close to the cap (within a few hit gems on the lower side, and essentially no leeway on the upper side).
4) So if your rating was much under the cap, hit gear was the "best." And if it was over the cap, it was the "worst." (Putting aside the option of swapping around for alternate hit pieces, which is besides the point here).

So we thought of that specific number, 263 rating, as having great significance in how we selected gear. In general, hit gear was thought of as being provisionally useful, based on where you were in relation to that number.

The point here is that this prior intuition must be discarded due to the presence of Reforging. Because now, in a word, all stats are fungible (in four words, they are fucking fungible as shit). Essentially, each additional point of hit, if you don't need hit, will ultimately manifest itself as a point of haste (currently our next-best stat). The converse is important as well: each additional point of haste, if you need a point of hit, will manifest itself as a point of hit. Note the symmetry: if I get one additional stat point, the result is the same regardless of whether that stat was hit or haste. When all is said and done, I get hit if I need it, otherwise haste.

The conclusions here are straightforward, subject to the limitations I'll discuss below:
1) When selecting gear, a point of hit and a point of haste are identical in value (after all, they produce the same end result after you do your reforging).
2) Your stat priorities do not change at the hit cap (which is 1742 in Cataclysm). A piece of gear is will be good regardless of whether you're above or below that number.
3) The main result here is that you should re-align your method of estimating the value of gear to look at the total amount of haste/hit/Spirit regardless of your current stats.

The main limitation on this principle is that you can only reforge 40% of the stat points on a single item (this is, of course, the only reason it matters at all what gear you actually wear). So if your unmodified hit rating is so low or high that you cannot reforge to the cap, the above breaks down. When will this happen?

A) The lower end (i.e. impossible to reforge up to the hit cap): There's no simple formula for this, since it depends on how much reforgeable haste/crit/mastery you have. But even in T1 gear, you can get over 1000 rating from reforging alone if you need to. There's virtually no way for your gear to be so bereft of hit that you cannot reach 100%. (Note also that you can reforge hit onto any piece, even those that already have it, since hit and Spirit are different stats).
B) The upper end (i.e. impossible to reforge down to the hit cap): This will be at 2745 hit. To see this, note that after reforging away 40% of the 2745, you have 1647. Adding in 95 from gems and enchants gives you 1742. This result may vary slightly based on the presence of blue sockets with good bonuses.

Conclusion

Rather than thinking of the hit cap as a single value at which we no longer care about hit rating, we now care about what I'm calling the hit reforging window. This window is a very wide range in which hit is no better and no worse than any other stat. The lower boundary of this hit window is very low (well under 1000), and the upper boundary is around 2745.

Within the window (where you are likely to virtually always be), evaluate gear as though a point of hit or Spirit were equal to a point of haste, ignoring the hit cap, and you will have a very solid rule of thumb for knowing which items are upgrades.