I think the Harris retirement is further compounded with the fact that Watson is no longer a threat and Siddle is not playing.
I know he has never been one of the big boys but it was never a bad thing having his services when required.
The absence of Siddle is also another issue. The Aussies only have Johnson with any real Ashes experience. As I have posted previously, the Ashes is more than just being a good cricketer. Starc has bowled well but wasn't backed up by Hazlewood or Johnson.
The difference down under last time was that Johnson, Siddle, Harris and co never let the England batsmen settle and this was similar towards the end of the Ashes in England where England were lucky to win the series at home.
I think the pitch is doing exactly what the ECB want it to do. I imagine they are chucking buckets of water over Lords, Oval e.t.c. as we speak, in the hope that England can keep battting themselves to a draw and hope that the Aussies balls it up just once.