Do managers understand?

But what of that other renowned Premiership manager, Sir Alex Ferguson of Manchester United? Was he right to pay extravagantly last summer for the young Atletico Madrid goalkeeper, David De Gea, who, from his first appearances, not least disastrously at Wembley in the pre-season Community Shield game, looked alarmingly prone to error and found it so hard to command his area when the crosses came in?-AP But what of that other renowned Premiership manager, Sir Alex Ferguson of Manchester United? Was he right to pay extravagantly last summer for the young Atletico Madrid goalkeeper, David De Gea, who, from his first appearances, not least disastrously at Wembley in the pre-season Community Shield game, looked alarmingly prone to error and found it so hard to command his area when the crosses came in?

Club managers have a thankless job. Praised and revered a moment only to be abused and critcised the next minute. But there are many a strange decisions taken by these wise men which even they can't comprehend. Over to Brian Glanville.

Bruised and battered by criticism after Arsenal's embarrassing defeat at home by Manchester United, in no small measure the result of his bizarre substitution, Arsene Wenger might find cold comfort in the words of that eminent 19th century British Prime Minister, Benjamin Disraeli: “The defects of great men are the consolation of dunces.” And defective it surely was at the Emirates Stadium for Wenger, inexplicably and surely irrationally, to take off the precociously effective winger, 18-year-old Alex Oxlade Chamberlain who had just splendidly set up the Gunners' equalising goal, scored by the usual player, Robin van Persie.

It was at this juncture, to the astonishment of the critical crowd and an anguished cry of “No!” from van Persie himself, that Wenger chose to make this strange substitution, pulling off Chamberlain and sending on the talented but unpredictable Russian, Andrei Arshavin. Who actually and disastrously set up Manchester United's equalising goal when he feebly touched a right wing cross from the ebullient Antonio Valencia straight to Danny Welbeck, who promptly and easily scored United's winner.

Never before had Wenger been subject to the current, jeering chant, “You don't know what you're doing!” But this, arguably, was not his solitary, costly mistake.

True, a spate of injuries to leading players has ravaged his defensive line. But what possessed him to field the unhappy and out of position Swiss international Johan Djourou at right back, where he was predictably taken to the corners by the quick, clever little United left winger, Nani? Not till half time did Wenger decide to spare him further punishment, putting in his place an 18-year-old debutant right back in the teenager, Nico Yennaris. Who did not disgrace himself, even though he was playing on his wrong foot.

As, the previous weekend, had been another teenaged full back in Ignai Miquel at Swansea, though on the left, rather than the right, where, all too predictably, the clever swift Swansea right winger, Nathan Dyer played ducks and drakes with him. You wondered what possessed Wenger, after the game, to praise the hapless Miquel's performance. Did this mean, you wondered, that Wenger was preparing to use him in the ensuing game against Manchester United, as well? In the event, it didn't happen; but poor Djourou stayed.

Wenger's selections this season have been oddly capricious. Shortly before the debacle against United, Leeds United, of the lower Championship division, came to The Emirates for an FA Cup tie. It was at this moment that Wenger decided to let van Persie, his one regular goal scorer, take off for a holiday in Dubai with his wife. Replacing him with the ineffectual Moroccan international, Marouane Chamakh, who once again made minimal impact.

Theo Walcott, the England right winger, who would prefer to play down the middle, was kept on the bench for 72 minutes and when he came on as a substitute, was deployed as usual on the right wing. At last his successor as a Southampton player, Chamberlain, all GBP12 million of him, looks like a wise and potentially fruitful buy. But taking him off in such circumstances as we saw in the United game was surely a dismal and discouraging portent for a footballer so young, however talented.

Wenger has made some odd transfers in the past, not least in the shape of the towering French centre back, Pascal Cygan, an expensive purchase and an ever erratic figure who once, in a European game at Highbury, headed powerfully and irresistibly into his own goal. He was steadily preferred to Matthew Upson, who'd been signed as a million pound teenager from Luton Town and who eventually, when transferred, became a frequent England international.

But what of that other renowned Premiership manager, Sir Alex Ferguson of Manchester United? Was he right to pay extravagantly last summer for the young Atletico Madrid goalkeeper, David de Gea, who, from his first appearances, not least disastrously at Wembley in the pre-season Community Shield game, looked alarmingly prone to error and found it so hard to command his area when the crosses came in? After a recent series of blunders, it's now transpired that he has defective vision and will need treatment. Apparently Ferguson knew this at the time, but still decided to buy him.

Then there was the recent surprise of suddenly re-launching the 37-year-old Paul Scholes, coaxed out of retirement and unexpectedly thrown into the furnace, as a sub, in the Manchester derby.

Where upon, poor fellow, he promptly gave away the ball allowing City to score. True, he's looked better since then and has coolly scored, but he didn't deserve to be thrown to the lions. Meanwhile, Fergie and United have embarrassing memories of an Italian goalkeeper who conceded disastrous goals. So it goes.