Arsenal got a good result against Aston Villa at the weekend but they have yet to sort out their defensive frailties.
Their options in midfield and attack are excellent - as shown by the sparkling play they showed to build 2-0 leads by half-time against Villa and also against Tottenham last weekend.
But a killer instinct is missing. Spurs should never have been able to find a way back into the derby game, and if Villa had had some more experienced players on the pitch, they might also have completed a comeback.
Arsenal's defence has changed completely in recent years.
The old days of Winterburn, Adams, Bould and Dixon are long gone. As a back four, they weren't pretty, but they were mightily effective.
A good performance started at the back. They cleared the lines, they knew when to step up, they understood when to pass the ball and when to just hoof it away.
The current Arsenal back four just doesn't seem to possess those same instincts.
Take Gael Clichy - he's a talented player but he lacks discipline and concentration. To me, he's representative of the Arsenal side in some ways - full of promise, but yet to make it count.
New signings Sebastian Squillaci and Laurent Koscielny have not convinced me so far, and if I were in Arsene Wenger's shoes I'd be looking to buy a quality centre-half, to partner Thomas Vermaelen when he returns, and a full-back.
And why not also give Kieran Gibbs a try? I've been impressed by what I've seen of him, especially at U21 level, and it would be good to see another British player break into the starting XI at the Emirates.
Wenger is his own man, though. He trusts his own judgement, and no amount of criticism in the press will change his vision. And whatever you might say about some of his decisions, you cannot question the strength of his convictions.
Can anyone else at the club question them, though? There are good people around Wenger at Arsenal - people who understand defending. His assistant Pat Rice was a good right-back in his playing career and there are Highbury legends like Steve Bould behind the scenes. They will be seeing those defensive problems which Gunners fans lament.
But it remains to be seen what changes, if any, Arsenal will make.
And this is without saying anything about Lukasz Fabianski in goal. I've made my feelings clear about Fabianski in recent weeks, and nothing has changed. Any defence will struggle to settle if you don't trust the goalkeeper's decision-making.
As I said last week, it's a very open title race this year. Chelsea are having their bad patch of form, Manchester United are top without having been at their best, and a number of other sides have come into it.
If Arsenal could tighten their defence, they could take advantage of a weak Premier League and make the step up in the title race.