Vincent Kompany of Manchester City lifts the FA Cup Trophy. Photo / Getty
This was history after all, the completion of the first domestic treble in English football, and yet something else felt even more significant: that even an FA Cup final with all its supposed magical imponderables can fall so utterly under the dominance of Pep Guardiola's team.
It was not a Cup final in anything but the name, barely a moment of it ever imbued with uncertainty or risk as far as Manchester City were concerned, rather it was just like any routine home win at the Etihad Stadium over the course of this season. One in which the away team dig in valiantly, do their best to execute a sensible plan of containment while accepting that this is only really a way of delaying the inevitable outcome.
The scoreline equalled the record for the biggest margin of victory in an FA Cup final that has stood since 1903 when Bury beat Derby County by the same score at the old Crystal Pace stadium, when Edward VII was on the throne, and the Wright brothers first got a plane in the sky.
This was the 51st domestic fixture or cup tie for City, and of those they have lost just four, the last at St James' Park on Jan 29. It is a remarkable run. Watford were never the lead candidates to beat them in an FA Cup final, although you might have been able to kid yourself as the crowds thronged Wembley Way that such an outcome was not implausible. Then the game started and it was evident that the difference in what both teams was capable of doing, even on a day like this, was simply enormous.
Perhaps the idea of City, a team that is so hard to disrupt, has occupied the minds of their opponents this season to the extent that they dare not do anything but defend deep and counter-attack quickly. Watford did that and it worked for a period and then after that they conceded six goals. In Copenhagen, readying himself for a concert that was impossible to cancel, Elton John will have been grateful for the small mercy of his own unavailability.
There was a hat-trick for Raheem Sterling, in his first FA Cup final a mile from where he grew up, but even that felt like it came second to the jaw-dropping one-sidedness of a match that stood as a monument for the season. In English football at least, City were unstoppable.
They had done everything right, or at least everything one can expect to do right when possession is down to 27 per cent and you are trying to stop the great threshing machine of English football from winning their third trophy of the season.
For the first 35 minutes, Javi Gracia's team stayed in the classic edge-of-the-area cluster, a low-block that just about engaged City when they got into shooting range. Watford's midfield only really stepped up to meet City once they got within distance and mostly they showed Guardiola's side down the right wing where Riyad Mahrez had a lot more of the ball than his counterpart on the left, Raheem Sterling.
Watford clearly felt that they could deal with Mahrez's general lack of pace and whenever he tried to go to the byline or come back on his left foot, the full-back Jose Holebas was supported by Roberto Pereyra. Most of the time, Mahrez opted to cross and Watford were happy to deal with that. There was no Sergio Aguero in the team, injury meaning that Gabriel Jesus had his place. Watford had very little of the ball but they will have expected that to be the case and they were comfortable.
They also had enough chances to make City think twice about leaving themselves too open to be counter-attacked. Abdoulaye Doucoure sprung the trap on 14 minutes and Watford made the chance for Pereyra that he might have scored with just Ederson to beat. But then this was not just a goalkeeper, but arguably the Premier League's best coming out at speed and seizing the initiative from the Watford man whose shot hit Ederson's legs.
Shortly before the first City goal, Doucoure had an appeal for a handball against Vincent Kompany that referee Kevin Friend waved away. The ball did strike Kompany's right hand, and the slow-motion did suggest that it was in an unnatural position but it was hard to argue it was deliberate, the defender in the act of tucking it behind him. Doucoure was booked for his protests and it felt like Friend was correct.
Then came the first goal, the ball originally lost in midfield by Doucoure who showed too much of it to the tenacious Bernardo. It went to the back post, was half cleared and came back via the head of Sterling. In the moment that it dropped to David Silva he seemed to push Kiko Femenia in the back before hitting his shot beyond Heurelho Gomes.
Even at that point all was not lost for Watford but they seemed to shrink, and the domination of the ball by City in the next 15 minutes must have felt overwhelming. Even so, it was hard to explain why Gomes came for Bernardo's back post ball with seven minutes of the first half to play. It was a good ball, and Femenia had lost its flight as well as Jesus behind him but even so had Gomes stood his ground he would at least have made the opportunity much more difficult. Sterling turned in his team-mate's shot on the line.
Kevin De Bruyne came on for a disconsolate Mahrez before the hour and from then on it became a humiliation for Watford. The Belgian scored the third when Sterling and Jesus combined, De Bruyne sitting Gomes down before going past him and finishing. De Bruyne created one for Jesus on 68 minutes and the floodgates opened. Sterling plundered two more in the last ten minutes as Watford cracked.
Five of the last six domestic trophies over the last two seasons have been won by Guardiola's team now, a momentum that will be hard for anyone to stop. Against a team that has to attack, City are lethal and what was left of Watford's confidence had drained away by the end. If was painful for Gracia's team, overawed and overwhelmed by a much more powerful opponent, much like the rest of English football this season.
Auckland City FC gave up five goals in the second half to Benfica.