Maurizio Sarri has not had much time to put his ethos across at Chelsea’s training ground.Photograph: Darren Walsh/Chelsea FC via Getty Images

Guardian writers’ predicted position: 6th (NB: this is not necessarily Simon Burnton’s prediction but the average of our writers’ tips)

Last season’s position: 5th

Odds to win the league (via Oddschecker): 14-1

The combination of the World Cup, which meant that some players will not report for pre-season until effectively after it has concluded, and the early transfer window have made this an extraordinarily difficult summer for a coach to move to a new club in a new country, assess his squad, instruct them in a completely new tactical system and make desired personnel changes. Add the speculation swirling around several members of Chelsea’s dressing-room, the drawn-out process of officially appointing him and his own predilection for information overload – at Sansovino, one of a number of humble lower-division teams on his CV, he was nicknamed Mr 33 because that was the number of set-piece routines he expected his players to memorise – and Maurizio Sarri’s task appears particularly formidable.

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Fortunately he is not prone to overhyping his likely impact. Back in 2015, when he was first approached by Napoli, Sarri delivered an unusual sales pitch. “We’re going to lose our first seven games,” he told Aurelio De Laurentiis. “I laughed,” the club’s president later remembered. “He smiled. The understanding between us was born in that moment.” De Laurentiis might not have been laughing when they did indeed lose their first game, to Sassuolo, and followed that with a pair of unconvincing draws. He approached Sarri again, wondering if it might be worth moving away from the narrow 4-3-1-2 formation that had worked well for the coach in the past but seemed unsuited to Napoli’s squad. “President, let me do it my way,” Sarri replied. “We might lose the first seven games, but then you’ll see what happens.”

Should anyone lose their first seven games at Chelsea it is fairly obvious what would happen, but happily Sarri’s subsequent success makes it seem extremely unlikely. In the end he did change his formation for Napoli’s next game, starting with a single striker and two wingers. They won 5-0, and then did it again in their next match. “The switch to 4-3-3,” De Laurentiis concluded, “happened because of me.”

Sarri has stuck with 4-3-3 ever since, and from Chelsea’s pre-season friendlies appears determined to use it again at Stamford Bridge. Sarri’s tactics worked phenomenally in Naples last season: they might have narrowly lost out to Juventus in the race to the Serie A title but in Europe’s top five leagues only Real Madrid, Bayern Munich and Manchester City averaged more shots per game than Napoli; only City, Bayern and Paris Saint-Germain bettered them on possession, only City played more passes and only at City, Liverpool and Juve were goalkeepers forced into fewer saves. If Sarri can bring this style to Chelsea, the results could be genuinely thrilling.

“I love this philosophy,” David Luiz admitted. “We play high, with lots of possession of the ball, in a technical way. He’s trying to help us every single day to learn quickly his philosophy, to do our best for Chelsea. A new philosophy always takes time, but it also depends on us. If we are dedicated every day in training we can try to learn quickly. It depends also on us.”

The arrival of Sarriball, as Napoli’s technical, high-speed style of play was christened, will be widely celebrated. Importantly, it is not only intended to be successful, but to be joyful. “My goal is to have fun as long as I am here and be competitive in all competitions,” he said. “Ours is not a sport, but a game, and anybody who plays a game starts doing that when they are young because it is fun. The child in us must be nurtured because this often makes us the best.”

This prioritisation of pleasure comes in complete contrast to Chelsea’s last couple of managers. The difference between the miserable demeanour exhibited by his predecessor-but-one, José Mourinho, this pre-season and the man who now sits in the Chelsea dug-out is jarring. It is hard to imagine the Portuguese asserting, as Sarri does, that the most important thing in life is “to have fun while you do your job”.

But the Italian’s arrival will not be celebrated by everyone at Chelsea, and the tactical overhaul will inevitably have casualties. Perhaps the great beneficiary of Antonio Conte’s switch to a 3-5-2 formation was Victor Moses, who sprung from relative obscurity to indispensability almost overnight. He appears likely to make the same journey in reverse now, while César Azpilicueta returns to right-back. Meanwhile Chelsea have been repeatedly linked with centre-backs, most frequently Daniele Rugani, which appears bizarre given their wild surfeit of options in that position, the fact that this year they will play with only two, and Sarri’s insistence that the transfer market is “a refuge for weak coaches” and that he will instead focus on “growing the players we have”.

“He is bringing a different style, a different formation and we just need to grow into it,” Cesc Fàbregas said. “We need time to re-adapt to a back four and to what the boss wants but I believe we’re intelligent players and players at the top level who will try to adapt as soon as possible.”

Fàbregas’s own place in the team is at considerable risk. Of the central midfield three Jorginho, Sarri’s trusted fulcrum who has followed the manager from Naples, is certain to start, while N’Golo Kanté is surely indispensable. This leaves room for one attacking midfielder with Fàbregas, Ross Barkley and Ruben Loftus-Cheek of the current squad competing for the place. Meanwhile Tiémoué Bakayoko, who exhibited none of the technical excellence that Sarri’s system demands last season, seems no more likely to excel, or even appear, this year.

With just days remaining before the season starts it is impossible to predict with any certainty the identity of their first-choice goalkeeper or any of Sarri’s chosen front three. Álvaro Morata has been typically inconsistent in pre-season – Sarri’s observation that he “did not play very well” against Perth Glory was refreshingly honest but not very encouraging. Meanwhile any or all of Eden Hazard, who would surely fit the Italian’s system beautifully, Willian and, at the other end, Thibaut Courtois might have left the club before the big kick-off.

One side-effect of the absence of many first-team players from much of pre-season has been that Sarri has been forced to play youth-team graduates in their place. The winger Callum Hudson-Odoi and defender Ethan Ampadu, both just 17, have stood out, while Chelsea also have Loftus-Cheek and Tammy Abraham returning from loan spells at top-flight clubs. Sarri’s priorities, in order, may be the pursuit of pleasure and of glory but, having spoken so enthusiastically of player development, if he fails to create a route into the first-team squad for the shining lights of a remarkable generation of youngsters then all hope that anyone will ever do so, already dimmed by years of failure, might be lost for good.