"Everyone thinks they have the prettiest wife at home." It's a resonant old line. Perhaps the pick of Arsène Wenger's classics. It evokes an era when he was at the peak of what seemed at the time to be manifold powers. Arsenal were Double winners with a team who welded the might of Sol Campbell, Martin Keown and Patrick Vieira with the marvels of Thierry Henry, Dennis Bergkamp and Robert Pires.

Sir Alex Ferguson, suffering the ignominy of watching the enemy win the title at Old Trafford in the summer of 2002, was not at his most generous. "They are scrappers who rely on belligerence – we are the better team," he scoffed, inspiring Wenger to respond with a flash of wit, throwing the media a juicy bone on which to feast in its insatiable analysis of the Ferguson-Wenger feud. At its height, they traded quips, insults and honours like two heavyweights.

If it seems like ages ago that they were arch-competitors, that is because it is. Almost a decade has passed since then, and although the barbs continued for a while, with each passing year the colour has faded, the spikiness has softened, as one of the fighters has evidently struggled to make his weight.

When Arsenal defeated Manchester United 1-0 at the Emirates during last season's title run-in, it was a rare success. United's dominance of this fixture – sometimes to the point of doling out humiliation – has become almost routine. It has reached the point where Ferguson feels a degree of compassion for the Arsenal manager. That has to be as clear a sign as any that Wenger's touch has gone awry. Nobody who lives in football's extreme world of winners and losers wants the sympathy vote. Nobody welcomes pity. Has it really come to this?

Wenger's image has taken such a pummelling since the start of the season, even people who would normally relish the schadenfreude have confessed to feeling sorry for him. Some critics felt moved to congratulate him on his team's safe passage into the Champions League at Udinese, as if they were relieved to see that he had found some refuge from the relentless pounding. "Well done Arsenal!" hurrahed the opening line from the Sun's match report, in all seriousness. Yet another clanging sign that things ain't what they ought to be.

Gutsy though their Champions League recovery was, and critical as it is to the club's profile, it would be foolish to allow a 90-minute shot-in-the-arm to paper over the cracks. Arsenal head to Old Trafford on Sunday with a thin squad stripped to the bone, still overloaded with problems that scream out for solutions.

But should all of them pile up at Wenger's door? While he bears a lot of the responsibility for their dysfunctional summer, others, too, should share the burden. Wenger needed help during this close season from other departments within Arsenal, but that help has not materialised. The scouting network, and the transfer negotiators, have never looked so weak. The board, which should have either backed him or forced him to shake things up before the Cesc Fábregas and Samir Nasri sagas took their toll, have sat back.

It is a myth that Wenger is the man who controls all transfer activity. First, he is dependent on his scouts for identifying and researching potential recruits. Apart from the obvious exceptions – Henry, Vieira and Nicolas Anelka were clearly well known to Wenger – in the main, the names and reports that are brought to him by the chief scout, Steve Rowley, are what persuade him to make a move for, say, a teenaged Fábregas. Or for that matter a Manuel Almunia, Denílson, or Igor Stepanovs. It is unusual for Wenger to watch much of little-known players in the flesh before they sign.

It appears that the scouts have not come up with a useful enough list of targets to work from this summer. Given that they knew they would in all likelihood lose a number of players, it was obvious they would need to do a fair bit of shopping. Considering most of the "shops" operate with a hint of poker school, and that agents block the shop front with all the charm of burly bouncers, it would have made sense to have numerous options to consider and to hit the stores quickly.

Yet Arsenal find themselves scrabbling about in the dwindling days of the sale, hunting for bargains where few remain on display. The experience of last summer with Mark Schwarzer, when they thought that if they hung on to the last moment Fulham would have to cave in (they did not), should have been a salutary lesson. That trick used to work. Not any more. The scene has changed since David Dein could pull transfer strings with the best of them and most players were instantly attracted to joining a winning team comprising the likes of Henry and Vieira.

It has been a tough summer for Dick Law, currently the chief deal maker, who has struggled to see through interest in a handful of major targets that were on the radar. Chelsea rang rings around him for Juan Mata; Bolton have played tough over Gary Cahill, rejecting Arsenal's latest bid on Friday; the Gunners did not even appear to make much of a play for José Enrique – available for less than Gaël Clichy and a real no-brainer purchase who instead went to Liverpool. Law lacks the global football contacts who packed Dein's address book, not to mention the ability to engage in smooth talk or hardball if appropriate.

Dein remembers how the atmosphere around the place could be exhilarated by a flurry of signings. In the summer of 2006, just after leaving Highbury, six deals bubbled along right until the 11th hour of deadline day. "Arsène has a lovely expression: You need some salt and pepper in the soup. You need to spice it up. This is not a perfect science," he says. "If we all knew the formula of Coca-Cola we'd all be multimillionaires."

Arsenal have a transfer budget of around £70m just from their summer sales. They are chasing an assortment of players, but it all feels worryingly late in the day and, so cack-handedly have they been functioning during this window, the Emirates crowd would be amazed to see the handful of needed signings arriving. Which brings us to the great unanswered question of life at Arsenal: Who really calls the shots when it comes to money available for players?

Depending on who you believe, either the board actively encourage Wenger to spend and feel frustrated at his reluctance, or Wenger does a good job in taking the flak and shielding the board from a financial reality that is much more sobering than they would like to admit.

The economics at Arsenal remain puzzling. And while the boardroom situation remains uncomfortable, with Alisher Usmanov's stake undermining Stan Kroenke's majority shareholding, nobody can put forward a clear message about how the club intend to be ambitious.

And so Wenger heads for Old Trafford, to take on his old nemesis at a time when United have just demonstrated that the youth project that has obsessed him can work wonders. Seventy million pounds for his thoughts as he scans the callow faces in the away dressing room and prepares them to do their best.