There are certain deep questions every football fan asks from time to time, while idly pondering the eternal vagaries of the cosmos. Why do the pages on Ceefax take so long to change? Is Stephen Carr still injured? How come Gerard Houllier sold Litmanen and hung on to Heskey? Who’s worse, Scotland or Northern Ireland? Why, for the love of God, won’t Mick McCarthy drop Ian Harte (preferably down a very deep well)?

Here’s another. What is the fucking deal with Diego Forlán? Why has he still not scored for Man United, after what feels like four years of trying?

Few things can be more guaranteed to dishearten United fans these days than the familiar sight of Forlán clambering out of the Old Trafford dugout and sheepishly limbering up, as he prepares to come on for another fruitless twenty minutes of haring around like a golden retriever chasing a frisbee.

Forlán has come on as sub in every game United have played this season. During the last campaign, he got seven starts and eleven sub appearances. In plain English, he has spent well over ten hours not scoring for United.

Another question: exactly how long is Ferguson prepared to let this continue? Against Leeds the other week, Forlán was again thrown on with 15 minutes left, and proceeded to take up a sort of floating midfield role, flitting between the two wings with utter ineffectuality.

Bizarrely, this unfortunate young man was responsible for one of the best strikes of the 2002 World Cup finals – a spectacular volley for Uruguay against Senegal. The footage of that marvellous goal, is starting to take on Loch Ness Monster dimensions in terms of plausibility.

These days, suffice to say that if Forlán fell into a bucket of tits, he’d come out sucking his thumb. His drought has gone on for so long that when or if he does finally score a goal for United, it’ll probably be greeted by a minute’s silence.

I jest, of course. If Forlán does ever manage to knock one in, the roar will be heard all the way to Montevideo. Despite what some of you might think, the denizens of Old Trafford are not stupid. They’re well aware that Forlán represents stg£7.5 million of untapped potential, and they wouldn’t mind being treated to some of it.

Indeed, when he scored with a stooping header near the end of the Champions League qualifier against Zalaegerszeg, the place erupted, only for a granite-hearted linesman to raise a flag for offside.

In that same game, United got a penalty a few minutes later. Forlán picked the ball up to give everyone a clear signal that he wanted to take the kick. Ruud van Nistelrooy was having none of it, ripped the ball out of his team-mate’s hands, and smashed the penalty home in his usual brisk fashion.

I remember John Giles making favourable noises on Network 2 afterwards, while nodding approvingly at van Nistelrooy’s selfishness. Giles said something to the effect that it was more important for United’s company policy to be adhered to (i.e. van Nistelrooy being the designated penalty-taker) than to be worrying about Forlán’s ego.

But surely, in this case, there was a wider picture? Would it not have been better all round to allow Forlán to get a goal on the board and give himself a bit of confidence, especially given that United were three up against a dismal and demoralised Hungarian side at the time?

It all makes one yearn for the killer instincts of Andy Cole, another man whose hesitancy in front of goal attracted much unfavourable comment – some of it fair – in his early days at Man United.

The difference is that Cole chose his third game in a red shirt to get off the mark. And despite having a rather ropey time of it over the next 18 months, once he finally got going there was no stopping him. He ended up netting 121 times for United, at the rate of a goal every second game, and is still the club’s leading scorer in Europe.

At least you can’t accuse Forlán of laziness. He tries, oh my God, how he tries. But it’s impossible to envisage any Cole-like improvement. His dry white season has gone on too long for his confidence to be anything but shattered. At best, United might get two or three goals out of the guy before Sir Alex cuts his losses next summer.