It is, officially, the worst scoring run of his professional life. When Wayne Rooney was withdrawn against Newcastle United on Monday it was the 13th successive game in which he had gone without the adrenaline rush he craves the most. In total, it has been 1,081 minutes – just over 18 hours – since his last goal for Manchester United or England.

Goals can have therapeutic qualities for centre-forwards, but it works the opposite way, too, and Rooney's current trough is a reminder that besides talent, courage, discipline and heart, confidence is the key that opens the locks in sport. And there is not a footballer around never to experience the odd moment of insecurity.

Maybe it is simpler than that and it is just that Rooney is struggling for fitness after a World Cup when he was nursing a bad ankle. Or, perhaps, it goes deeper than that and there is something else troubling him.

Everyone seems to have a theory, much of it supposition, some pure guesswork, and plenty of it hypocritical considering that the stampede of people rushing to judge him includes quite a few members of the writing profession who were frothing about him being "world-class" only a few months ago – a fuzzy and unsatisfactory term, in any case, and one in this instance that ignored Roy Keane's observation that this vibrant, prodigiously gifted player still has "a hell of a lot to do, Wayne has achieved nothing".

All that can be said with certainty is that Rooney has never experienced such a morose scoring drought, the previous worst being a 12-game run – 1,002 minutes in terms of match-time – from December 2005 to February 2006, ending when he scored twice in the Carling Cup final against Wigan Athletic.

"I say it time and time again; strikers live by their goals," Sir Alex Ferguson said today. "When they are not scoring, they think it is never going to come. Then when they [goals] come, they think they are never going to finish. They are straightforward people, you know. And Wayne is no different from any other striker."

The United manager is entitled to be concerned, not just that his richest source of goals has temporarily dried up, but also when contemplating Rooney's lack of vitality and, at times, his dreary body language. Ferguson, as an ex-striker, knows the kind of thoughts that can permeate a footballer's mind when shots start to go astray and the perimeters of the goal suddenly seem that little bit smaller.

Rooney's last goal was clocked at 7.46pm in the Allianz Arena on 30 March, in a Champions League quarter-final against Bayern Munich. That was 143 days ago and since then he has played 492 minutes for Ferguson's team and 589 for England, incorporating almost a month in South Africa that was ultimately little more than a personal ordeal.

One source close to Fabio Capello has spoken privately of Rooney, contrary to reports at the time, being just as bad in training as he was on the pitches at Rustenburg, Cape Town, Port Elizabeth and Bloemfontein. Capello's feeling is that it was as much a state of mind as it was related to the forward's ankle. Rooney being Rooney, he had genuinely believed he would have a brilliant tournament but, as it became apparent it was not working out, the feeling is of a man who withdrew into himself and, maybe for the first time in his career, let the pressure eat away at him. Much of it is educated guesswork, though. Capello and his coaching staff remain perplexed about what happened.

Rooney is avoiding the media, so we will have to wait for his own explanation. But, in his defence, these are very much the embryonic stages of the season and it would be knee-jerk in the extreme to argue (as Piers Morgan has in another newspaper) that Rooney is incapable of emulating the 34 goals he scored last season, en route to cleaning up the player-of-the-year awards.

He has, after all, already provided us with a moment to remind us why he was so revered in the first place. It came 41 minutes into the Community Shield, drilling a ball into Antonio Valencia's path to leave him with a scoring chance it would have been almost impudent to turn down. There are times in football when a pass can be the greatest source of beauty, and the beauty of this came in the subtle glance over his right shoulder, the anticipation to know where Valencia was running, and the self-belief and ability to play it "blind". Few players are blessed with this peripheral vision - "playing with wing-mirrors," to use Jamie Redknapp's description of Paul Scholes - and Rooney deserved better than the brilliance of the moment to escape so many observers.

But Rooney was the exception when Frank Lampard, Steven Gerrard and Didier Drogba quickly slotted back into being outstanding Premier League players, as if their dishevelled performances in the World Cup were a trick of our imaginations. Rooney was full of running against Newcastle but not too much came off and it was no great surprise when he was substituted. Ferguson explained it on the striker still "being short" of match fitness, but if that is genuinely the case he cannot be far off now, so the excuse will be wearing thin if he turns in another peripheral performance at Fulham .

"There is no such thing as a lack of confidence," Rob Andrew once said, in his days as an England rugby player. "You either have it or don't." Rooney does, but confidence is also a delicate thing and, for the man the United crowd call the "white Pele", it might not be until his next goal that it flutters back into his life like a bird coming down from the eaves.