I have always rated Hussey and thought of him as a batsmen worth persevering with through a lean patch.
Siddle is a different story. Prior to this match, he hadn't played since January and he just walked in ahead of Bollinger, who would be first picked in my team if fit. Australia needs Bollinger for his menace in my opinion.
Nobody honestly can say that they foresaw what happened with Siddle. It was great bowling- none of the wickets were cheap. But I don't think anybody can rub his performance in the face of his critics because based on the evidence we had prior to the test, there is no way that he deserved to be selected ahead of Bollinger. For example
v Pakistan in Hobart- he was the best bowler in the test
v Pakistan in Sydney- he was the worst
v Pakistan in Melbourne- he was the worst
v West Indies in Adelaide- he was the worst
v West Indies in Brisbane- he was the worst
So he turns in a couple of great performance 1 in 3 (or, often 1 in 6 by innings) and is terrible the rest of the time. I'm taking nothing away from Siddle for those superb performances, but when Siddle turns in those performances, his fans can fly their flag, but they seem to be forgetting, or ignoring, about the cost of having him in the side.
I'd much rather face an Australian side with Siddle in it than Bollinger.
In any event, given Siddle's performance in the first innings and Johnston's form, the heat must be transferred to Johnston now. If he doesn't perform in the second innings, you'd have to imagine Bollinger would replace him