I think Lehmann was an excellent choice too and I have never felt the urge to judge him on this or even the next Ashes.
There are too many long-term issues with this team to fantasise that a change of coach will suddenly turn players into world-beaters.
You can't make a silk purse out of a sow's ear.
Watson - Finished
Rogers - Stop gap at best
Kwajaja - WIP
Hughes - Walking wicket against spin
Clarke - One decent batsman
Smith - ???
Of our top six in a years time i would be very surprised if more than 2 are still playing at the top level. Lehmann isn't going to be able to do much until that happens.