The Arsenal forward has divided opinion ever since he was called into England’s World Cup squad aged 17, but that was nine years ago and the doubts remain

Amid all the conspicuous consumption of Baden-Baden in 2006, the dancing on tables and the parades of personal trainers, there was an incongruous constant, a small shaft of sanity in a mad, mad world.

Most nights, Don Walcott would take his seat outside the small curry house. He was amenable, approachable and seemed a little bemused by the circus he and his son had suddenly found themselves a part of. It’s startling now to think that was over nine years ago, that that’s how long Theo Walcott has been a promising footballer. Everybody’s still waiting for Theo.

Walcott is 26. He cannot be a great hope forever, living in a limbo of possibility, forever on the verge of breaking through without ever quite doing it. This is a player who, in 2008, eviscerated Croatia for England, scoring a hat-trick as they lost a competitive game in the Maksimir for the first time, yet only once has he managed 10 league goals in a season.

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It hasn’t helped of course that, despite his requests to play as a central striker, he has spent much of his career operating on the flank, and he has been particularly afflicted by injury: since joining Arsenal in January 2006, he has missed 119 games – more than three full league seasons – due to various injuries. Aside from signalling the score to jeering Tottenham fans from his stretcher after rupturing cruciate ligaments – an endearingly gentle riposte, as if Tim Henman had unveiled new heights of mischievousness – he has barely registered a complaint, working hard to make yet another comeback.

In the two seasons before this one he started a total of 13 league games. Little wonder his career feels as though it has never quite got going, that even as others have risen and fallen, he remains forever the fragile teenager with the searing pace who exploded into the public consciousness with a goal on his full debut, for Southampton away to Leeds, while still only 16. The injuries, at least, seem never to have sapped his speed.

The question, though, is whether he can ever be anything more. After all, this is a player who fell into football almost accidentally; he did not grow up yearning to be a footballer. When he was nine he played in goal because he thought saving penalties would be exciting, only to realise that there were not all that many penalties and that he found the other parts of goalkeeping a bit dull. He played his first competitive game, for Steventon Boys in Oxfordshire, at 10 because they were a player short and, to the amazement of everybody, not least his father, scored a hat-trick.

Facebook Twitter Pinterest Theo Walcott scores for Arsenal against Olympiakos in the Champions League. He has 10 goals from his past 12 starts. Photograph: Kirsty Wigglesworth/AP

He was a natural, but the doubt with naturals is always whether they will develop; when their capacity to play the game is instinctive, to what extent is it possible for them to learn or develop? There have, recently, been some promising signs. Given more of an extended run at centre forward, he has scored 10 goals in his past 12 starts. He played the full 90 minutes against Chelsea and Olympiakos, two of the past four games, having not done so in his previous 32 appearances. In that Olympiakos game, he and Alexis Sánchez were pretty much the only two Arsenal players to emerge with any credit.

He is getting stronger, but he still gets caught offside too often. There are those who will argue his finishing is improving, and perhaps it is, but the truth is he has always been a decent finisher.

Over the past three seasons, he has scored with one of every 6.67 shots; over the two seasons before that, he scored with one of every 6.95 shots (that said, a rough average is a goal every nine shots, so he’s doing something right).

For Arsenal, perhaps the most important aspect is not just what Walcott does himself, but what he means for the shape of the side.

Olivier Giroud, up to a point, offers a physical presence, an outlet from the back and a target for crosses – although, as Ashley Williams and Sebastián Coates showed towards the end of last season, he can be bullied. His 44 league goals for Arsenal have come at a rate of one every seven shots.

Walcott will never hold the ball up as Giroud does, but his pace creates space for others, and maximises Mesut Özil’s passing ability – so long as the opposition leaves space behind it for him to exploit. Against a defence that sits deep, though, as Olympiakos did in the latter stages on Tuesday, Walcott’s greatest strength is negated. Manchester United – who Arsenal host on Sunday – employ a defensive line that tends to be higher than most, but it is not radically high and it may be that if Arsenal dominate possession, United sit deep and Walcott finds himself frustrated. Assuming, that is, he starts.

When Walcott does not have space to attack, his threat is limited: he is good but far from great. His pace is extraordinary, but there’s nothing else that makes him stand out. Have injuries slowed his progress, or just slowed the process of judging him, of moving him on from being a prospect into something a bit more definitive? Much as he seems a sensible, nice, professional lad, the sort of person who deserves to succeed, there remains a fear that he is just a little too nice - the anti-Diego Costa, perhaps – lacking the hard edge to turn ability and promise into anything more meaningful. That he is, in a sense, the embodiment of Arsenal.

When Walcott was 13, playing at Southampton’s academy, his father bet him £100 he couldn’t score 30 goals in the season. Going into the final game, against Tottenham, he was on 28. Walcott scored and then, with five minutes to go, he won a penalty. One shot, from 12 yards, for £100.

He hit the bar.