@DeviousUn When we start the tuning pass, you'd know, because there will be changes to many specs all at once. Estimating two PTRs from now.- Greg Street (@Ghostcrawler) August 6, 2013
If you weren't already aware, the way Blizzard develops the classes on the PTR is as follows. They start off with mechanics changes, so, say, for example, they looked at shaman spread healing, and decided it still needed buffs. The mechanics changes were to alter Chain Heal so it didn't decrease in effectiveness as it bounced, and to make the cooldown incurred by glyphing it far lower. Those are mechanics changes. There have been others, too, of course, but the main thing to remember is that these relate to how spells work, the mechanics of spells.
Next up, it's the tuning. So in the case of our earlier example, that would be adjusting how much Chain Heal actually heals for as it bounces merrily around the raid. Damage and healing is a little all over the place on the PTR right now, and many players are concerned, hunters being a fine example, but the truth of the matter is that the maths is only just beginning. Next step will be to take all the numbers and start fixing them so that DPS shaman can't one-shot you any more (awww) and hunters no longer hit like wet noodles.
The question is, of course, what does this mean for the patch date? Greg reckons we've got another two patches before the tuning begins, so that would likely take us close to the end of August. My money's on October for 5.4's arrival. How about you?