Many believe that Wayne Rooney's decline over the past couple of years is down to him not knowing his best position. In truth, though, he has never known his best position but it is only recently that it has proved a significant problem.
When Rooney emerged as a 16-year-old at Everton in 2002, he played as a straightforward second striker. He did the running alongside Kevin Campbell, an old-fashioned target man who won aerial battles. The young Rooney had licence to drop deep when he liked, or sprint in behind.
Rooney replicated this approach in the early part of his England career, making his name alongside Michael Owen. Although Owen was a very different type of player to Campbell, Rooney played roughly the same role as he did at club level and spent much of his time driving forward into goalscoring positions, rather than pulling the strings.
Upon moving to Manchester United in 2004, Rooney generally played a more withdrawn role. With Ruud van Nistelrooy dominating and occupying a position inside the six-yard box, Rooney buzzed around in pockets of space behind and was sometimes fielded wide if Sir Alex Ferguson played a front three.
But the pair didn't work particularly well as a partnership; Rooney later admitted he felt Van Nistelrooy was unhappy after he arrived because the team was no longer based around the Dutchman. When Van Nistelrooy departed in 2006, Rooney and Cristiano Ronaldo stepped up.
Over the following three years, Ronaldo evolved from an inconsistent winger into a goalscoring machine. Rooney, meanwhile, was forced to play second fiddle and changed position regularly during this period.
Sometimes he played as a striker, sometimes as a No. 10 and, on some occasions -- particularly in big Champions League games -- he was deployed on the flank, where he earned praise for his tremendous work rate. He sacrificed himself for Ronaldo until his teammate departed for Real Madrid in 2009.
Having essentially played second fiddle to either Van Nistelrooy or Ronaldo for the first five years of his United career, from 2009-10 Rooney became the main man at Old Trafford. His strike partner was now Dimitar Berbatov, although some of his best performances came when Ferguson omitted the Bulgarian to beef up the midfield, leaving Rooney alone up front.
He became a tremendous header of the ball and it was in this season, when playing as more of a striker than ever before and scoring 34 goals in all competitions, that Rooney won the PFA and FWA Player of the Year awards for the only time in his career.
Things changed the next season, however. Berbatov had a peculiar campaign, finishing as joint-top Premier League scorer but omitted from United's Champions League final squad, while Javier Hernandez's arrival meant Rooney often dropped into a No. 10 role.
He remained there in 2011-12, often playing behind Danny Welbeck. Rooney's return of 27 league goals remains a career best, although he didn't offer much more than goalscoring, despite playing between the lines, and set up just five goals overall.
There were also concerns about Rooney's lack of defensive work, previously considered his strong suit. At international level he notably failed to pick up Italy's Andrea Pirlo in the Euro 2012 quarterfinal, with Joe Hart screaming at him to mark the deep-lying playmaker.
Accordingly, Ferguson bought Shinji Kagawa, a proper No. 10, but the United manager's subsequent signing of Robin van Persie meant Rooney continued to play deeper and with some success. Even under David Moyes, when most of his teammates suffered a drop in form, Rooney managed 17 goals in league 29 games, again from a withdrawn position.
He performed better than is remembered at the 2014 World Cup, creating one of England's goals and scoring the other. Significantly, however, he was shifted to a wide-left position in the opening game against Italy, likely because Roy Hodgson knew he wouldn't mark Pirlo properly.
Raheem Sterling did that job instead, but Italy's most dangerous player then became right-back Matteo Darmian, Rooney's future United teammate. The problem had simply shifted according to Rooney's position.
Under Louis van Gaal, Rooney's role became increasingly confused. Initially fielded upfront, he was then repeatedly deployed in a midfield role. Although Rooney had previously spoken of his willingness to drop back later in his career, Van Gaal's peculiar system, which essentially asked his midfielders to man-mark their direct opponents relentlessly, did nothing to teach the basic positional characteristics required and Rooney's form dipped significantly.
Hodgson's decision to use him in a midfield role as part of England's 4-3-3 formation at Euro 2016 appeared a very late call and didn't work well; Rooney offered careful passing but little penetration against deep-lying defences.
Since then things have become strange: New United manager Jose Mourinho said he wouldn't field Rooney in a midfield role but, after he played poorly as a No. 10, did just that.
In his first and only game as England boss, Sam Allardyce started Rooney in midfield in a 4-3-3 against Slovakia, then as a No. 10 in a 4-2-3-1 for the second half before later saying it "wasn't up to him to tell Rooney where to play," which was a bizarre take and didn't correspond to what happened anyway.
Over a 14-year career, Rooney has rarely gone more than two seasons in a regular position and, since he joined United, there have been three distinct phases.
From 2004-09, Rooney was hard-working, versatile and tactically disciplined enough to be shifted around while the team was based around other players.
From 2009-14, he was largely the main man and his fine scoring return -- 93 goals in 150 league games -- was enough to either build the team around him, or to "accommodate" him despite concerns about tactical discipline.
But, since 2014, Rooney has lost any trace of dynamism, which means he's less of a goal threat and he also lacks the discipline and stamina of his early years, which means he's no longer a useful tactical weapon.
"I'm so confident, I'm happy to play anywhere on the pitch," Rooney once said. "I've offered to play centre-back when United have been hit by injuries, I've even offered to play full-back."
At times, it's felt like United and England managers would be willing to try that, simply to crowbar Rooney into the side. On the basis of recent form, though, he simply doesn't deserve to play and his versatility has become a problem rather than a virtue.