In March 2010, Barcelona travelled to Arsenal for the first leg of the Champions League quarter-final between the two sides. Goalless at half-time, the game was dominated by the Spanish giants, the holders of the competition, and they took a deserved lead through Zlatan Ibrahimović only 23 seconds after the restart before the Swede added a second 13 minutes later.

This was Pep Guardiola’s Barcelona at their scintillating best, and they really should have ended the game four or five goals up. Yet 2-2 was the final scoreline in London as the hosts crawled their way back into the tie, thanks largely due to the introduction of Theo Walcott on 66 minutes. Just three minutes after coming on, the Englishman latched on to a through ball from Nicklas Bendtner and slotted calmly under Victor Valdés to reduce the deficit.

He played a key role in the equaliser too, floating a cross into the box for Bendtner to nod into the path of Cesc Fàbregas, who had his legs taken from underneath him by Carles Puyol. The Arsenal skipper picked himself up to smash home the resulting penalty and secure a draw, but the plaudits were heading Walcott’s way.

His energy, pace and skill throughout his cameo had Maxwell, one of Barcelona’s best players for the first hour and amongst football’s most decorated players, looking lost at left-back. Had he played from the start, Arsenal may well have won the game.

Barça would claim a 4-1 victory in the second leg at the Camp Nou with Lionel Messi scoring all four, but Walcott’s performance at the Emirates had stuck in the mind of the Argentine. Ahead of another Champions League meeting the following year, he commented: “I can only speak from experience but he was one of the most dangerous players I have ever played against. Barcelona players are not scared easily but I can tell you that when we played Arsenal last season he truly worried us. We were so in control of the game at 2-0, with all respect Arsenal were not even in the game. Then Theo came on and changed the game. He pretty much single-handedly salvaged a draw that night.”

This was who Theo Walcott was meant to be. A player discussed as, and indeed by, one of the best in the world.

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At times throughout his career, Walcott has been the untouchable force that many thought he would be. He scored twice in the north London derby in 2012 to help Arsenal beat Tottenham 5-2. In the same year, his hat-trick was decisive as the Gunners came from 4-0 down to beat Reading 7-5 in one the craziest League Cup games in history. In a 7-3 demolition of Newcastle, he scored three and assisted two more. He’s scored in both the FA Cup and League Cup final. In total, only 14 players in Arsenal’s history have netted more goals for the club than Walcott’s 108.

On the international stage, a 19 year-old Walcott became the youngest player to score a hat-trick for England when he netted three away to Croatia in 2008. He came on as a substitute against Sweden at Euro 2012, scoring a goal within three minutes before setting up Danny Welbeck, dragging England from 2-1 down to 3-2 up in the process. Incredibly, Walcott has the highest win percentage with the Three Lions (70.2 percent) out of any player to have earned more than 40 caps. Indeed, he has never lost a competitive match with the national side.

He’s certainly had his moments. The statistics above speak for themselves. But you’re still very much left with the feeling that, at 29 years old, Walcott could have achieved more. This may partly be due to the fact that the expectations and placed on him at such a young age are simply impossible to reach.

When you become the most expensive 16-year-old on the planet and are then picked for England’s World Cup squad just four months later, having not even played a minute in the Premier League, your potential sky rockets. When the comparisons to Lionel Messi and Thierry Henry come along, it’s boosted even more, especially when you inherit the Frenchman’s shirt number at a club where he holds legend status. It’s not ideal when you’re still developing and finding your feet in the professional game.

In an era when the media place expectations on teenagers after one good game, when fans think they’re qualified scouts and when every touch, goal and mistake is available to view and scrutinise online, players like Walcott are almost set up to fail. When you consider that Wayne Rooney, a five-time Premier League winner and England and Manchester United’s all-time record goalscorer, is still thought of by many as having not lived up to his potential, then what hope is there for Walcott?

Walcott has had his fair share of injury troubles, too. In September 2015, physioroom.com compiled a Most Injured Premier League XI of the 21st Century and included Walcott as they revealed that he had missed 1,030 days out through injury since signing for Arsenal.

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The largest single period of absence in that total came when the forward missed nine months of football after rupturing the anterior cruciate ligament in his left knee in an FA Cup clash with rivals Tottenham in January 2014. He may have smiled smugly and gestured the 2-0 scoreline to the Spurs fans to as he was proudly stretched off, but that injury couldn’t come at a worse time for the 24-year-old.

He was arguably in the form of his career having registered double figures for both goals (14) and assists (10) in the league in 2012/13, and started the next campaign by registering five goals and five assists in 13 games, including a brace away to Manchester City. He was in the perfect position to finally appear at the World Cup, having failed to make it off the bench in 2006 before being harshly left out of the squad by Fabio Capello in 2010. It could be argued that Walcott hasn’t been the same player since. He certainly hasn’t featured, or scored, as regularly.

Since that research was carried out, Walcott has been far from injury free, missing over a month of action in both 2015/16 and 2016/17 with a calf problem. The latter campaign also saw the winger suffer a hamstring injury which, added to a two-week bout of illness last season, means Walcott has been sidelined for a further 100 days or so in the last three years.

Not only do these absences go some way to rationalising the inconsistency that Walcott is often criticised for, but they also say something about Arsenal’s contentious injury record Whilst he may have been at Everton for just nine months, Walcott has missed just one league game in that time. When you also consider that two further Arsenal players, Abou Diaby and Tomáš Rosický, also featured in the most injured Premier League XI of the 21st century, questions over the Gunners’ training methods start to appear.

Whether that’s a harsh assessment or not, it is probably true that staying at the club for as long as he did – 12 years in total – did restrict Walcott from reaching his full potential. In 2006, the teenager couldn’t have picked a better club to continue his development. It was hard to argue with the way that Arsenal were developing the talents of Cesc Fàbregas, Robin van Persie and Mathieu Flamini, all players who joined the club aged 20 or under.

At the time of Walcott’s arrival, the Gunners had won two Premier League titles and three FA Cups in the previous four seasons. Four months after he joined, they reached the Champions League final. There was no indication that a move to a new stadium would see these achievements dry up – quite the opposite.

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But dry up they did, and Walcott, for some, came to embody the Arsenal side that continually underachieved, going nine years without a trophy and failing to get past the round of 16 in the Champions League in seven successive seasons, before eventually dropping into the Europa League.

As the club stagnated, so did he. Arsenal quickly became an environment that limited his ability instead of allowing it to develop and flourish. Arsène Wenger’s powers waned and he struggled to set up the team to compete at the highest level. He wasn’t sure how to use Walcott, how much freedom to give him, or what position to play him in. Maybe he was never sure.

Walcott was seen as a striker from an early age. He was taken to the 2006 World Cup over established centre-forwards Darren Bent and Jermain Defoe. He continually spoke of his desire to play down the middle. Multiple England managers and Wenger continually claimed that chance would come. It never did, but for a few games here and there, and you have to wonder how that has affected his career.

“It is a case of having trust in me up front,” Walcott plead in 2012. “I was signed as a striker and it is about time, I want to play up front. I have learnt my game on the wing. When you look at what I did last year I think I can do even more. Hopefully I will be given the opportunity. I am desperate for it.”

Again, opportunities in the role were few and far between, even after the departure of Van Persie. Wenger’s vision of Walcott making a Henry-esque transition from winger to striker was simply not emerging. By 2016, Walcott had given up trying. “I have told the manager that I want to be known for playing on the right again,” he said. “I want to make my position on the right – that’s where I know I am now.”

It was the closest thing that a polite, reserved Walcott came to criticising what was happening around him. Incredibly, Wenger epitomised the bizarre, infuriating nature of the whole situation by playing him upfront the very next game.

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It may have taken the departure of Alex Oxlade-Chamberlain, another Southampton academy product that Arsenal signed as a teenager, to Liverpool in the summer of 2017 to make Walcott realise that the grass was perhaps greener elsewhere. Not that he wasn’t being given hints. After Walcott admitted that Crystal Palace “wanted it more” following a 3-0 defeat at Selhurst Park in April 2017, Wenger’s fury was evident in the fact he handed the winger just one further league start out of a possible 27 games.

Walcott would follow Oxlade-Chamberlain to Merseyside, but to Everton, in January. The grass has indeed been greener. The 29-year-old has made 11 league starts in a row at the start of this season – the last time he achieved that at Arsenal was March 2013. In total, he’s made 24 league starts in nine months at Goodison Park. His final two years at the Emirates yielded the same number.

This plethora of opportunities, which resulted in three goals and three assists in the second half of last season, and two goals and two assists at the start of the new campaign, seemed to have allow Walcott to rediscover his old self. But a recent dip in form has left many questioning his place in Everton’s line-up with the inconsistent adjective once again being bandied about. Ademola Lookman, the young, fresh and exciting winger that Walcott once was, is after his starting spot.

Following Walcott’s poor performance against Manchester United in which he appeared to be at fault for the two goals Everton conceded, Graeme Souness ranted on Sky Sports: “Theo Walcott is 29 years old; when do you give up with players?”

Whilst Souness was perhaps a little harsh, it isn’t a wholly inappropriate question. Walcott has just two FA Cups and two Community Shields to show for his 12-year career. He has been stuck on 47 England caps since November 2016, and a recall looks unlikely as Gareth Southgate pursues a youthful and revolutionary squad.

So as he nears his 30th birthday, Walcott is entering a make or break period in his career. A move away from north London has given him a new lease of life somewhat, but can he make a run of form stick with the Toffees? He was meant to have won the treble with Arsenal and the World Cup with England by now.

By Olly Allen @OllyAllen_