Well, nuts. Well done Australia. Better team won, but in a large part it was a tale of two crap batting orders, with one outstanding star on one side who virtually batted single handedly. Replace Steve Smith with a normal batsman from either side, and there is very little between the two teams (although Cummins has been immense). Losing Anderson didn't help matters either.
As with the series Down Under, it has been the key moments that England have lost. They got Australia 110-8 or thereabouts at Edgbaston. They were in a decent position in the first innings at Old Trafford more than once. They were on top at Lord's. But in each case, Australia have managed to knuckle down and keep them out, in most cases thanks to Smith.
England haven't helped themselves by continuing to pick batsmen who are hopelessly out of form and can't bat like test match batsmen. Whereas Australia were probably the most prepared they'd ever been. They have had players in the county championship and A tours preparing for this. Whereas England haven't been able to call on any replacements, as most haven't played first class cricket since July.
In theory, in could still be a drawn series, but England will have to play better than they have done so far. Winning the toss and putting up a good first innings total wouldn't hurt (Australia have won three of four tosses so far. Doubt it would have made much difference).