I don't really know about a jump in quality all round, either. Obviously Australia's standard has dramatically lifted, and we're not carrying a Dizzy or Kaspa in the bowling lineup, even if Lee has been a bit unimpressive in general (good today tho). And the batting's gone through the roof, with the introduction of Hussey in particular.
But England's bowling has been pretty indifferent in the main, with the odd really good spell here and there. The surfaces probably haven't helped, nor the absence of Simon Jones, Flintoff's hot and cold spells and Harmison's listlessness. I guess it all depends on what you class as "quality of cricket" - if you mean batsmen having it more their own way, then maybe, though that to me is reminiscent of the flat road = great wicket
judgement that commentators always seem to make. As I said in another thread related to the closeness of the contest
, I think the conditions, certainly in the first half of the series probably made England's performances look better than they were, simply because the first three tests were pushed into fifth days.
Basically though, I think you've got one team raging in top form, and the other well below their best. I'd agree with howard that the last series saw far more of a tug of war between bat and ball, which generally, IMO produces a better standard of cricket as it's more a zero-sum, push me, pull you kind of contest. The conditions definitely offered more for the bowlers (than the first three tests did here at least), but 400 and thereabouts totals were still being scored.
Beyond this, captaincy has played it's part, too. When you're not quite up there, personnel-wise (in comparison to your opposition) you really need a good captain. Last time, Vaughan appreciably had the better of Ponting, while this time around, Ponting (who is still very defensive, but whose onfield presence and manipulation of his field has certainly improved) really had Flintoff's number.
A tight contest doesn't always mean a better quality of cricket, but I certainly wouldn't describe the quality on show from both sides here was high.
It's obviously not regarded as outrageous a comment as it was last series, but I'd say it's pretty obvious that we haven't seen England's best, and that's had a fair say in the outcome. Of course, saying that about Australia in '05 brought jeers, because it was taking something away from England's victory.