His loss to combined forces was nothing to be proud of. King's Landing was virtually undefended - save only by the gold cloaks and the token Lannister forces not committed to fighting Robb in the Riverlands, and Stannis' navy was by far the largest in eastern westeros. For him to have been so royally walloped means he messed up badly. The Rose only joined the battle after it was all but decided anyway. Tyrion had for all intents and purposes won the battle with the fire-oil-stuff (what was it called again?).
Not positive about whether he still holds Dragonstone - evidence could lean either way, but i hadn't heard he'd lost Storm's End as yet. Though with its token garrison, i would certainly not be able to hold out for as long as Stannis himself held it for.
You must have read it differently then i did, yes Tyrions defense was good, BUT Stannis could NOT have attacked differently AND KS would have fallen if it where not for the appearance of the Rose and the Lion.
The goldcloaks where bassicaly defeated at that moment (also they consist of 5000 folk wich is not at all little, and Tyrion had led the bulk of the remainder of the troops out in a last attempt to hold stannis off. Stannis would have taken KS if the troops(Lion and Rose) had not arrived at that particular moment. Even so, ithe fact remains that that was his ONLY notable defeat, and that he has won several important battles in his life.
Wether he holds Dragonstone is a questionmark, but i rather believe the intell Littlefinger got then the intell cersei got. So for me Dragonstone still stands, He holds Storms End (after having it retaken, wich is a mean feat, it does not really matter how he did it - shadowbaby, to the outside world it still is a huge victory), and after his defeat at the blackwater, he has made a wise decision going to the wall. In AFFC we do not know much of that part of the world, but to me it is clear he is proabably establishing a powerbase to be reconned with there. Moreover Dragonstone is strategically very important, and the fact that he holds Storms End still is of great importance as well, it is not a castle wich one can take lightly, and he still has influence to the nobles there.
Stannis is atm a safe bet, cause the Lannisters are crumbling, the Rose is uncertain, though we do know certainly that they are beseeched at the moment by the Ironborn. The north is a mess atm, and the Boltons as of yet have not enough control there. Riverrun is a hotbed for trouble as well, i doubt the Lannister Frey will control it for long. And Dorne well, it has bassicaly closed its borders since Robert got the Throne, and are plotting against all those who claim the throne for anyone besides Targaryens in the long run.
