It turned out that you can teach an old dog new tricks. Arsene Wenger seemed weighed down by obduracy, a man resolutely refusing to learn the lessons his critics felt he needed to heed. While the rest of the footballing world changed, Arsenal stayed the same.
Until Wenger switched tack, surprised his doubters, and suggested he had been secretly studying Antonio Conte. He adopted a back three, a policy he had ditched in the summer of 1997 after inheriting Bruce Rioch’s 3-5-2 formation.
Imitation proved the sincerest form of flattery and the most effective method of combating Conte's system. Arsenal seemed to line up in the FA Cup final with inferior personnel to Chelsea but won most individual battles, played 3-4-2-1 better and secured the silverware.
Perhaps it showed football’s cyclical side. Chelsea’s time playing 4-2-3-1 came to an abrupt halt when Arsenal deployed the same system to rather greater effect and beat them 3-0 last September. They go into a rematch with both remodelled.
Chelsea, who are able to unleash an expensive new centre-back in Antonio Rudiger, won 27 of 32 league games playing 3-4-2-1.
A May setback at Wembley Stadium can be deemed an off day. Arsenal won nine of 10 after Wenger’s spring switch.
As they included three notable scalps – both Manchester clubs and Chelsea – it could be deemed an unqualified success.
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Yet Manchester United fielded a weakened team because of a focus on Europe. Manchester City had a goal wrongly ruled out and twice hit the woodwork. The margins can be narrow.
Arsenal only conceded seven goals in those final 10 games which, after letting in 23 in the previous 10, represented a marked improvement.
Players such as Gabriel, Nacho Monreal and Rob Holding flourished as, at Wembley, did Per Mertesacker. Yet, in stats compiled by the website Arseblog, Arsenal conceded slightly more big chances per game against the same opponents with a back three.
One difference was that fewer went in, another that they created 1.3 more per game. They became more prolific, but that was partly due to Alexis Sanchez, scorer of eight goals in those 10 matches.
While Wenger is adamant the Chilean is staying this season and rationalised “it's always in your interests, even if you have a short contract, to do well", he may be relying on an unsettled figure. Sanchez only returned to training on Tuesday and is unlikely to start on Sunday, but the record buy Alexandre Lacazette should.
Yet Arsenal’s fortunes might rest less on attack than that reconfigured defence.
Whereas Conte had years of experience organising a back three, whether with Juventus or Italy, Wenger does not. His back three has looked frail in pre-season and the experiment of using midfielder Mohamed Elneny in defence has been abandoned.
Their best-laid plans have been unlocked by Chelsea before. First Didier Drogba and then Diego Costa assumed the mantle of the scourge of Arsenal. The latter scored even in the FA Cup final defeat.
His replacement, Alvaro Morata, is neither as physical nor as combustible. “Maybe less of a goalscorer than Costa but he can create more,” Wenger said on Thursday.
At least he need not worry about the injured Eden Hazard, while Pedro is a further doubt, and at least Arsenal’s best defender is available: Laurent Koscielny’s suspension for his dismissal against Everton will be served in Premier League games instead.
He missed the start of last season, which Arsenal began in chaotic fashion by losing 4-3 to Liverpool. It set the tone for a season when defensive issues were only resolved by copying Conte. Yet change seemed to come more from desperation than inspiration.
The test is if it, like Chelsea’s switch, will prove sustainable and successful.