At Edgbaston, the match difference was two runs. In the third Test, the Aussies only drew by virtue of the rain, really. As you said, England thoroughly deserves their victory. Especially since he would have been playing in his first Test series,
I'd have backed Hussey to do relatively poorly, especially since vastly experienced, tough Test batsmen like Hayden, Langer, Ponting, Martyn, etc. didn't come close to equalling their career averages. Even Kat was relatively experienced and came into the series in reasonable nick, yet left it a shot-duck.
Plus, the reserve swing was clearly more effective against lefties so Hussey would have had to contend with that. It's all idle speculation and no-one has any way of knowing for sure but England's bowling, as good as their batting was, made the difference. If a line-up like the Aussies had for that series can struggle, anyone can and Hussey, I'd hazard, would have too.