On the surface, the opening weekend of the Premier League season offered few surprises or unexpected results.

Manchester City comfortably beat an Arsenal team in transition, Liverpool put four past West Ham United for the third time in a row, Tottenham Hotspur recorded a routine win against Newcastle United, and the newly promoted teams struggled.

However, with so many new faces – on the pitch and in the dugout – we learnt plenty about the tactics the 20 Premier League clubs will deploy in the 2018/19 season. Here are three lessons we learnt from matchday one, as well as our pick of the best and worst tactical feature of the week:

1) Ozil's new role and Arsenal's pressing hints at bright future under Emery

There was a moment in the second half when Petr Cech waved his defenders forward and opted for a long goal kick, prompting cheers from the crowd; some Arsenal fans will need to show a bit more patience. Yes, they were sloppy passing out from the back, chaotic in midfield, too easily handed Manchester City space on the flanks, and deservedly lost 2-0. But there were plenty of positives to take from this game.

Firstly, Arsenal's energetic pressing and urgency to counter-attack marked a major departure from Arsene Wenger's tactics, which was pretty impressive considering how little time they have had to adjust to life without their longest-serving manager. Clearly the players are willing to listen and learn, while the admittedly wild Matteo Guendouzi typified a new aggression in the 50-50s.

But the most important change was Mesut Ozil's new role to the right of a midfield three, a deeper position than the German ever played under Wenger. From here, Ozil received the ball deep in his own half and looked to play a quick vertical pass forward to trigger a counter-attack. Emery clearly recognises the potential of Ozil instigating the breakaways from a more withdrawn role, with Aaron Ramey playing as a second striker, making runs ahead of Pierre-Emerick Aubameyang.

Ultra-narrow, gut-busting counters will be a key feature under Emery. Ozil and Ramsey have important – and brand new - roles to play.

2) Keita offers Liverpool more dynamism going forward and will help Klopp to shut games down

Naby Keita was sensational on his Liverpool debut on Sunday afternoon, controlling the tempo of the match with the gracefulness and ease of a player that has spent his entire career in English football. His energy, weaving runs through midfield, decision-making, and calm one-touch passing will help Liverpool maintain their high-tempo football this season.

Jurgen Klopp's midfield has been crying out for a player like Keita. His sudden turn of pace and ability to hold the ball for a long time – dragging opponents towards him before finally playing the pass – can create the quick counter-attacks that are usually uncommon against defensive mid-table opponents. His outside-of-the-boot pass to Sadio Mane ahead of the opener was a special moment, evidence of his confidence and technical ability.

Equally important was his position on the left wing during the final 20 minutes. Klopp withdrew Roberto Firmino and replaced him with Jordan Henderson, moving Keita into a wide defensive position to shut down the match. This is one area Liverpool need to improve, and in Keita they have a player who can replace one of the forwards in a conservative fashion.

3) Spurs use new formation to accommodate Lucas Moura – with mixed results

Lucas Moura was labelled as a right winger on the Sky Sports graphic, but in reality he played almost as a striker alongside Harry Kane in a narrow 4-3-1-2 formation. Dele Alli, Eric Dier, and Moussa Sissoko were a flat three in the centre with the Frenchman leaning heavily to the right in order to cove the spaces left by Moura and Serge Aurier, erratically bombing up and down as usual.

It was certainly an unexpected switch of formation from Maurico Pochettino, possibly designed to target a perceived weakness on Paul Dummett's side as Kenedy fails to track back. The result was, in the first half, a fluid Spurs performance with plenty of position rotation that prevented Newcastle United from settling into a defensive block. Two goals in the opening 20 minutes suggest Rafa Benitez's side struggled to adapt.

However, as the game wore on Spurs became more formless, losing their coherence as Lucas increasingly wandered into a free role, popping up on either flank and making the likes of Alli and Eriksen work harder around him. The Brazilian is certainly a wildcard: Pochettino eventually substituted him for Mousa Dembele and the game calmed down, Newcastle's chance of an equaliser rapidly receding.

Best of the week – Richarlison

A harsh red card reshaped the late kick-off in Saturday in a game that had threatened to end in heavy defeat for the hosts. Wolverhampton Wanderers were tactically naïve on their return to the top flight, playing with an extremely wide formation that gave Everton the opportunity to counter-attack with venom.

The Wolves front three didn't move too well while the wing-backs hugged the touchline in advanced positions, leading to lots of long diagonal passes that didn't really advance their play. This expansiveness afforded room for Richarlison on the counter; the Brazilian's run down the left won the foul that led directly to his opening goal.

In the second half the hosts bizarrely dropped off into a flat 5-4-1 and begun to lose the 50-50s. It was during this period of backing off and hesitating that Richarlison skipped through the defence to score his second, highlighting exactly why he is worth the money Everton paid this summer. The 21-year-old's decision-making, and sense of when to punish the opposition, was a standout feature of his game under Marco Silva at Watford.

Worst of the week – West Ham's high defensive line

There is a worry that West Ham have once again plumped for over substance, have chased the glamourous flair players rather than patched up the squad's flaws. On Sunday they were extremely soft and slow in midfield, as usual.

Of greater concern was that remarkably high defensive line, a dogmatic approach to defending that cost them dearly over and over again, leading directly to the second and third goals. As David Preece highlighted on Twitter, their rigid, unintelligent attempts to stay high reached a bizarre zenith in the second half:

West Ham taking their high line to new levels of silliness by holding a line higher than the their two-man wall for this free kick. pic.twitter.com/4ayUsRovUE — David Preece (@davidpreece12) August 12, 2018

Manuel Pellegrini, a once superb manager who semi-retired in China two years ago, perhaps symbolises the club's transfer policy. Does the Chilean have the fire in his belly to organise West Ham? The lack of nuance to that high line suggests it could be a difficult campaign for the Hammers.