I don't think Anderson is off form, or at least far from it, and Broad has bowled well. The ball and pitch reduced the swing available, but they could both still control a session.
Johnson was all pace and bounce, he never swung it, but flinging it in at right angles seemed to help. On the plus side, he's never kept it up for a whole series. I remember Tremlett scaring Aus with rib bouncers, at least he can do it for more than a couple of sessions a year. Even without Johnson I doubt Eng could have put up a score. They're lucky Patinson still isn't fit.
If they're going to win on flat pitches, they need to manage short 90 MPH balls and even consider playing four seamers (Finn, Onions, Bresnan). Dropping Swann at Perth wouldn't be a reflection on anything other than the pitch. Root can mix it up between them. Even then, it all depends on the batsmen coming out the blocks late again.
Johnson will start throwing them wide before long. Not before doing a couple of photoshoots of his tattoos and teabagging by the Ausie press.