It was perhaps the most expensive swap in football history, and one of the more convoluted and sentimental. Romelu Lukaku traded Everton for Manchester United. Wayne Rooney exchanged Old Trafford for Goodison Park. The Merseysiders banked £75 million while the Mancunians promptly surged to the top of the table.
Sunday's meeting of the clubs brings a mass reunion, which also takes in Marouane Fellaini, Morgan Schneiderlin and Michael Keane, and a comparison. The striking signings seem statistical success stories. Lukaku is the Premier League's top scorer. Rooney can claim a distinction that has eluded even the prolific United newcomer: He has scored 100 percent of his side's goals in the division this season, even if that only amounts to two.
Yet there is a difference and a paradoxical one. Between them, United and Everton appear to have inverted the usual rules of football business. The focus on the transfer market is such that buying can seem the answer to everything. Yet United have replaced Rooney, their record scorer, without signing anyone to fill his role. Everton have acquired two forwards without replacing Lukaku.
One argument is that they have replaced each other, but it is not as simple as that. United manager Jose Mourinho made it clear last season that he did not consider Rooney a No. 9: even when Zlatan Ibrahimovic was not available to lead the line, Marcus Rashford and Anthony Martial were preferred to the club's record scorer.
Once Mourinho's mind was made up, he only relented in the final three matches when he had abandoned interest in the Premier League to focus on the Europa League. That amounted to pragmatic use of resources and a romantic reward for Rooney's longevity rather than a football choice.
Before then, he was substitute and squad player, operating as a No. 10 and off the left. United have hired no one to fill those roles. It seemed in spring that Mourinho could pay his captain the compliment of replacing him with Antoine Griezmann, officially the third best player on the planet in 2016 and at a fee that would have made him among the costliest ever. But interest in the France international was put on hold. The preference was to spend the biggest bulk of the budget on a No. 9, not a No. 10, after Ibrahimovic's knee injury forced a change of plans. Enter Lukaku instead.
There was no arrival to fill any of the attacking midfield berths. A winger was wanted, whether Ivan Perisic or Gareth Bale. None joined. Thus far, none has been needed. Mourinho could simply use players United already possessed. Henrikh Mkhitaryan started the season in Rooney's old role as a No. 10. He recorded five assists in the first three league games, making the Armenia international officially the most creative player in the division. Rashford and Martial have been in a private battle to nail down the spot on the left. Martial scored twice in the opening two games, despite figuring for a total of 25 minutes across the two. Rashford has goals in his last two outings.
The closest United have come to replacing Rooney has been to re-sign the injured Ibrahimovic and to grant him the No. 10 shirt that the Englishman wore for his last 11 seasons at Old Trafford. Even when fit, the former Sweden striker is likelier to be Lukaku's deputy than an extra option in the two or three slots behind him.
If United found the answer within, Everton are yet to show they have found the answer outside Goodison Park. Sandro Ramirez was one forward addition and, at £5.3 million, ought to prove a bargain but has made an uncertain start. Rooney was another and, at his unveiling, Everton manager Ronald Koeman mentioned that the 31-year-old could play in four positions: one was as a No. 9.
Thus far, however, Rooney has only had passages of play as the furthest man forward as Koeman has changed tactics and personnel in search of a solution. He has rued the fact that Everton missed out on a third striker, potentially a target man such as Olivier Giroud who may have replicated at least some of Lukaku's considerable contribution.
And so far, despite Rooney's well-taken goals against Stoke and Manchester City, Everton have lacked potency as well as the pace Lukaku used to offer. Only Dominic Calvert-Lewin has brought speed and only the 20-year-old has stretched defences; if United have already concluded the solution was internal, Everton may have to adopt a similarly organic approach to finding a successor to Lukaku.
Because the comparisons are stark. Everton outscored United last season. Now there are already 10 league goals between them. Lukaku has scored twice as many goals as Everton. Albeit after a daunting quartet of fixtures, Koeman's charges have had the fewest shots on target; Lukaku has had two more on his own than his old club, while United rank second. Their creative contingent is functioning fine without Rooney. They rank first for crosses and through balls, whereas, with him, Everton come 14th and 16th respectively.
Perhaps it is an indication of Rooney's decline and marginalisation at Old Trafford but there is something quietly remarkable that United have not replaced their 253-goal record scorer and have emerged stronger. Perhaps it is a sign of Lukaku's excellence but there is something predictable that Everton have lost a 25-goal, £75m striker and seem weaker.
Both sides may feel nostalgic as acquaintances are renewed, but Everton are alone in missing what they have lost.
Richard Jolly covers the Premier League and Champions League for ESPN FC. Twitter: @RichJolly.