On Monday Night Football in October 2018, Gary Neville conducted an analysis of Anthony Martial in which he attempted to figure out why the Frenchman was still struggling to fulfil his potential.

How, he asked, could a player with so much talent remain such an enigma?

Martial had exploded onto the scene in stunning style with his memorable debut goal against Liverpool at Old Trafford in 2015, but three years later he was drifting in and out of the Manchester United team under Jose Mourinho having lost his place in the French national side too.

Neville's conclusion was that, while Martial ranked among the very best in terms of speed, skill and finishing ability, he would only reach a truly elite level if he could transform other areas of his game. "What drives me crazy about him is his off-the-ball work," he said. The application was not there and nor was the understanding of where to be and when to be there.

Neville's analysis came to mind during Manchester United's goalless draw with Wolves at Old Trafford at the end of last month.

It was just the latest game in which Ole Gunnar Solskjaer's side have failed to find a way to beat a deep-lying opponent, but this time they could call on their £68m signing Bruno Fernandes. The issue was not so much a lack of creativity in midfield as a lack of movement further forward.

"Everybody wanted to the ball to feet," said Solskjaer afterwards. "Nobody was getting in behind. We just played outside their box."

Solskjaer did not single anyone out, but there could be little doubt about the identity of the primary culprit. By the end of the game, Manchester United had attempted 15 shots but not one of them had come from their striker. Martial simply didn't get himself into the right positions.

It could be seen on numerous occasions throughout the game, but it is best encapsulated by a passage of play in the 22nd minute, which started with Fernandes picking up possession on the right-hand side of the box, an area from which he provided a steady stream of assists for Sporting Lisbon.

Fernandes has space to send over a cross with his stronger foot, but seeing Martial flat-footed and motionless in the middle, he opts to play a short pass to Juan Mata instead.

Mata then looks up himself, waiting for Martial to make a run, but still there is no sign of movement.

Like Fernandes before him, Mata is left with little choice but to play it backwards. Fred lays his pass off to Andreas Pereira, and another opportunity to work the ball into the Wolves box passes United by.

Martial's performance prompted an incredulous reaction from Jamie Redknapp in the Sky Sports studio. He said: "I looked at him and I thought, do you understand what's at stake here?" But in truth it is just what we have come to expect from a player who, in between the moments of brilliance, remains as perplexing as ever.

During his analysis last season, Neville challenged Martial to do more off the ball, saying that improving his running stats would be an "easy-fix" which could be the difference between scoring 10 or 20 goals in a season. But there is no sign of improvement. Martial was covering 9.1km per 90 minutes at the time and his numbers are identical now.

Martial is therefore still bottom of the pile in terms of distance covered among Premier League forwards of comparative style and quality, and the sprinting data is even more alarming.

Martial's running stats are still lower than they should be

His pace and explosiveness are two of his best attributes, but he is not using them nearly often enough and the statistics prove it. Martial is making far fewer sprints than his contemporaries - including team-mate Marcus Rashford, who, by no coincidence, has racked up nearly twice as many Premier League goals as him this season.

The Wolves game was not the first in which Martial has been a static target in the final third either. Neville described the lack of movement in United's forward line as an "absolute joke" during the 3-3 draw with Sheffield United at Bramall Lane in November, and he is not the only former player to have identified Martial as a major part of the problem.

"He is talented, and he's not a bad kid, but the problem he has is that he looks lethargic all the time," said Ryan Giggs earlier this season. "He looks casual, as if he's not bothered. When it comes off and he's doing brilliant things, you think it just comes naturally. But when it's not, you think he's not running, he's not trying, he's not working hard enough, he's not holding the ball up."

Martial has scored 12 goals in 28 appearances this season

Solskjaer, though, has defended Martial repeatedly, insisting as recently as a few months ago that he has "absolutely everything in his locker" to become Manchester United's No 9. "One of the reasons he wanted to stay here was because I told him I saw him as a central striker," he added.

It should be noted that Martial has had his moments this season, not least his goals in the wins over Chelsea and Manchester City and his double at home to Newcastle. Solskjaer might also point to the statistics which show that only Raheem Sterling and Pierre-Emerick Aubameyang have converted a higher percentage of chances since the start of the last campaign.

But on top of everything else, there is still little clarity over Martial's best position. He has spent the first half of the season playing almost exclusively through the middle - a role he has long coveted - but he still seems more comfortable when dropping deep or drifting wide to take defenders on and drive United forward on the counter-attack.

It is hardly surprising, then, that his heatmap does not resemble that of an out-and-out striker - or that United were willing to go ahead with a deal for Odion Ighalo, a 30-year-old former Watford player who has spent the last three years of his career playing in China. The need for a penalty-box presence had become urgent and Solskjaer knew it.

For Martial, a player who, at 24, should be approaching the peak of his career, it is likely to mean another positional shift and more question marks over what, exactly, the future holds for him. Can he find it within himself to increase his work-rate? Can he learn when and where to make the kind of runs that separate the most prolific goalscorers from the rest?

Until he does, this story of unfulfilled potential is likely to continue.

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