When football historians look back over this season in years to come, it will be interesting to see how important they view the signing of Alexis Sanchez to Manchester United's ambitions.
It is striking to think that there were many who were concerned by the Chilean forward's transfer from Arsenal -- this writer included -- and some who did not see the need for it altogether. Sanchez, it was feared, would rapidly reduce the playing time of Anthony Martial and Marcus Rashford at a key stage of their development -- a fear which turns out to have been justified.
Yet, in this era of warp-speed news cycles, it's easy to forget just how sensational his switch to United actually was. He had been courted for months by Pep Guardiola, but had also long been the subject of a private and protracted approach from Old Trafford. And so, in one of Ed Woodward's finest moves yet -- a phrase which two years ago would have been difficult to imagine, given Woodward's initial failures in the transfer market -- Sanchez found himself in red instead of blue.
Sanchez was set to join a City squad already creaking under the weight of its firepower -- he would have found himself among the ranks of one of the most devastating attacks the top flight has seen, alongside Sergio Aguero, David Silva, Kevin de Bruyne, Gabriel Jesus, Leroy Sane, Raheem Sterling and Bernardo Silva.
Perhaps he looked at that cast and did not believe he would be a regular choice, despite Guardiola's presumed arguments to the contrary. What is for sure, though, is that United's need for him was far greater than that of their local rivals.
Sanchez, like Romelu Lukaku and Jesse Lingard -- no coincidence that they are seemingly Jose Mourinho's first-choice front three -- is someone who can still thrive in a largely unstructured attack. His first few games, though, raised minor alarm. For the most part, despite his considerable efforts, he was far below par -- his passing and his shooting were equally wayward, and he had little understanding of the movement that his teammates were making around him. Given the vast salary Sanchez commanded, he was expected to settle at once -- but it would have been unrealistic for him to do so.
In recent months, he has looked much more like the player Mourinho and Woodward relentlessly and successfully pursued. Most notable have been his showings in United's "big" matches, most particularly the 3-2 derby win over Manchester City. In this fixture, he played a leading role in United's comeback from two goals down, and provided an exciting glimpse of the team's future. He thrived amid chaos, sending in the free-kick that Chris Smalling steered home for a remarkable winner, and when making decisions in the final third he was the very soul of focus. His runs, so often mistimed before that day, were perfectly in sync with his fellow forwards.
Though Sanchez's understanding with Lingard has only just begun to thrive, it has been striking to see how frequently he and the England international find each other in space -- in a couple of respects they have similar approaches, unafraid to shoot from distance and very keen to play one-touch football at speed. That economy with the ball and diligence without it seem to be key to Mourinho's attacking approach, a welcome change from the pedestrian football that has often drawn frustration from United supporters.
Mourinho will call for patience, given that his side finished second in the table and have reached the FA Cup final, and that Sanchez is still finding his feet -- he ended up with two goals in 12 matches, and three goals in 17 appearances in all competitions.
Much seems set to come from him, and not too soon -- City outscored United this season by 106 goals to 68, a difference of 38. Chile's loss, though, is United's gain -- since their inability to qualify for next month's World Cup in Russia means that Sanchez, for the first time in years, will have a full summer off. That's no small matter, given that the last few seasons have seen him competing furiously at international level, in the process claiming two Copa America titles at the expense of Lionel Messi's Argentina.
United have some way to go to catch City, but the addition of Sanchez -- an almost unrivalled force of dynamism -- may just be the first step in the fightback. If so, the January transfer window of 2017-18 will be regarded as one of uncommon drama, and where the most thrilling of gambles handsomely paid off.