With all the smoke swirling around Ashburton Grove right now – courtesy of the charred crater that was once our first-choice midfield – it appears we have lost sight of one of last season’s fundamental shortcomings: lack of requisite personnel in defence.

Of course, a back four of Kolo, Gallas, Clichy and Sagna was comfortably enough to munch the probing fingers from most teams’ attacking departments last term, providing counter-attacking flair to boot and securing us a top-four berth with little trouble. And that’s fine – if “top four” status is all one is after.

But in the handful of make-or-break games against genuinely dangerous opposition, the iron-clad reasons for our failure to reach Silverware Summit were plain as day. And it wasn’t our inability to score goals.

Gallas outmuscled, outfoxed (and, in a first for social science, out-w*nkered) by Drogba at Stamford Bridge, Kolo inexplicably trying to dry-hump Babel as the clock ticked down at Anfield, and Philippe “Give Me Strength” Senderos giving Torres an acre in the box in that same sorry game. THESE were the moments that mattered. And they will happen all over again.

Senderos’s nightmare moment is the most inexcusable from a managerial point of view. Because it wasn’t even a blunder: it was simply a thunderous mismatch in quality. Stick a player like Fernando Torres in the box against a player like Philippe Senderos and, eventually, the net will bulge in the worst way possible. Torres might even get a goal too.

You cannot play Philippe Senderos and expect to win crucial games – it is as simple as that. No amount of bedding-in, of experience, of incremental improvement is going to change the fact that players like Ferdinand, Vidic, Terry, Carvalho et al are in a different class.

Obviously, we won’t be facing the Torres’s of this world every game. But that is precisely the point. When it comes to the business end of paramount matches, we do not have the necessary quality to ensure the level of performance we desire. And an envious look at our rivals confirms the fundamental, trophy-deciding nature of this difference.

Rewind to Moscow (you remember: that little town we were apparently “on our wayyyy” to all season?). Apart, of course, from the moment he sat bawling on the turf like an incontinent blue dumpling, dreams whistling past the post into a black hole of eternal regret, John Terry rose time and time again in the Champions League final. It pains me to say it, but it’s a fact. Blocking, nodding, snuffing-out, hoofing and Fort Knox-ing his team onwards, the match continued as long as it did largely because of the height, presence and savvy of the Chelsea captain – in precisely the same way that Ferdinand and Vidic stood immeasurably tall at the other end of the field.

I sat in constant thrall at a stunning contest – and in constant anguish at the chasm of quality separating Arsenal’s defensive abilities from those on display. There’s no getting away from it: Gallas, Toure and Senderos alone will never, ever, hit the mark if they are our squad’s sole central defensive offering. Screw fretting about whether Walcott and Vela will make sweet on-field love together this season – we desperately need a taller, more athletic, no-fannying-around-now, statement-of-intent, central defensive signing. And quick.

The gap is not about to close of its own accord. Unlike ours, United and Chelsea’s centre-backs will all continue to deliver genuinely “commanding’’ performances. Games where a succession of imposingly assured headed clearances swiftly render any policy of “sticking it in the mixer” from the opposing team utterly redundant. Games where, as a result, an imposing structural calm seeps through the team from back to front within 15 minutes. Where corners take on a sense of routine inevitability rather than resembling nail-bitten O.K. Corral episodes.

Such luxuries are alien to this current Arsenal team. And these are the details that will make the difference.