If I recall, when you exit a form, you're not given a GCD, so you can instantly change to another form basically preventing any actual CC to come about -- which is probably why it's considered an immunity.
Subtletly is made for Mobility and Feral Druids have more uptime than we do even though our damage is skewered. Your damage isn't. Either mobility or damage has to be reduced to make it fair. Uptime with perm. dots that deal good damage isn't acceptable.
except that sub has worked in competitive pvp, it worked for an entire expansion. ferals have never worked in competitive pvp. even in wrath when they had high damage AND high mobility, they were STILL one of the worst pvp specs in the existence of wow.
so far people are only complaining about 1v1 scenarios, which:
A. dont matter and
B. ferals have always excelled and been grossly overpowered in despite ferals being complete garbage in competitive pvp.
it is just funny how far people will go out of their way to ensure that ferals will always be a joke spec in pvp when there isnt even a single piece of relevant data that shows them to be op in any meaningful context.
now, i have no doubt in my mind that blizzard will kneejerk nerf ferals into the ground. they always do. people complain about how powerful ferals are in the beginning of every expansion, blizzard guts them and they become a joke spec before they even have a chance to pvp with it. even if blizzard left them alone, ferals might be viable for one arena season, and then degrade back to a joke spec for the rest of the expansion.
why? for the simple reason that ferals scales HORRENDOUSLY with bigger brackets, and always will. now i will say that is not blizzards fault. the very things ferals have enjoyed about the spec have ensured that it will never see the light in larger scale battles. changing that to make it viable in larger brackets will pretty much mean removing most if not all of the aspects that made feral fun, and they will make the feral community mad. it is a lose-lose for blizz.
that said, blizzard has tried to help ferals out over the years, in wotlk mostly. it is just everything fell way short.
there are a few changes i would make to ferals, not because i think they are op but because their mechanics are either silly or inconsistent. such as rake bug being fixed, tiger fury no longer giving bonus damage to bleeds (this would nerf the first set of feral bleeds by 15% and be one less clunky mechanic for ferals in pve), and nerfing maim to be more inline with kidney shot (which should have been done the moment CS/KS changes were announced).