Graham Potter managed to fail with every decision he made on his Brighton return, Nottingham Forest fell into a passive state at Arsenal and Jack Grealish was the difference for Manchester City. Here's five lessons we learned from the Premier League weekend...

1) Rodgers goes too deep and gets his subs wrong

It seemed as though Brendan Rodgers had taken a gamble on Erling Haaland passing his late fitness test on Saturday, because his extremely deep 5-4-1 formation appeared to focus almost exclusively on defending within the penalty area. It meant that Leicester were far too deep, unable to get out of the Manchester City counter-press and therefore appear as though they were simply waiting to be beaten.

A very poor first half from Kiernan Dewsbury-Hall compounded the issue; he was not showing for the ball, which meant Youri Tielemans was effectively the only passing option for a back three that had clearly been instructed to play short passes only, in the hope of drawing Man City forward to create space behind Rodri. Leicester were locked in, and Rodgers' half-time substitution only made things worse.

Subbing Dewsbury-Hall for Nampalys Mendy was the wrong move, as it meant Leicester remained in the same trapped shape, and indeed it was a clumsy foul from Mendy that gave City the freekick from which Kevin de Bruyne scored. Credit to Pep Guardiola for clearly instructing Jack Grealish to be more individualistic and creative in the dribble after the break (his run led to the Mendy foul), although it seemed almost certain Man City would score eventually.

That Leicester were far better in the final 15, pushing Man City back with an aggressive 4-4-2, only heightened the sense that Rodgers had gone too negative for most of the game.

2) Conte opens up significantly to inspire comeback

You have to admire Antonio Conte's stubbornness. There is increasing anxiety around Tottenham Hotspur that his negativity is holding the team back, and yet for a very winnable game at managerless Bournemouth Conte went for a 3-5-2 formation without any of his more creative players; Oliver Skipp was given a start ahead of the more nuanced Rodrigo Bentancur, and Ivan Perisic was left on the bench in a 3-5-2 formation.

But Conte made the necessary changes in the second half, switching to a 3-4-3 with Lucas Moura added to the front line as Bentancur and Perisic came off the bench. Bournemouth, sitting deep as usual, had invited pressure all game and Spurs just didn't have the quality to break through the shell until those more intelligent attacking players came on. Perisic assisted the equaliser before Bentancur scored the late winner.

Here was further evidence that Conte needs to open up and take a risk on more assertive front-foot football – but it was also evidence that he needs serious reinforcements in January. There just isn't enough quality outside Tottenham's first 11.

3) Potter underestimates former club's strengths

One would expect Graham Potter to intimately understand Brighton and work out a game-plan to negate his former club, but the new Chelsea manager got virtually every decision wrong in a humiliating 4-1 defeat against Roberto de Zerbi's side.

Throughout the campaign Brighton have been stronger down their left flank where the in-form Leandro Trossard has been helped by the overload of bodies attacking this side, yet Potter picked a particularly weak set of players to defend here. It is no surprise Trossard ran rampant in the first half as Christian Pulisic struggled in an unfamiliar right wing-back position, exposing Trevor Chalobah. Worse still, Conor Gallagher was fielded in an inside right position, further weakening a side of the pitch that only really contained Pulisic and Ruben Loftus Cheek.

The midfield selection was also an error. Brighton's extreme pressing under De Zerbi has seen them dominate possession against almost every team they have played so far, yet Potter decided to leave Jorginho on the bench, plumping for a less assured partnership of Loftus-Cheek and Matteo Kovacic. Finally, despite Brighton looking very vulnerable on the counter-attack under the gung-ho De Zerbi, Potter left his most direct attacker Pierre-Emerick Aubameyang on the bench, and took Raheem Sterling out of the front line.

4) Danks' repeat formation reveals the tactical gap

Unai Emery will take charge of Aston Villa for next weekend's game against Manchester United, and the board will be pleased to have hired somebody so quickly. The most important thing after the disastrous spell under Steven Gerrard is to find a true tactician, and Emery is one of the most diligent and effective tacticians in the game, spending dozens of hours analysing opponents before each game.

Clearly that wasn't the approach of Aaron Danks, who picked the same team in the same formation as the one that beat Brentford 4-0 the weekend before – despite Newcastle United representing a completely different challenge. That meant that, again, Villa were much wider than usual in a 4-2-3-1 formation and more expressive on the ball.

Newcastle have become one of the best transitional teams in the country, which makes Villa's tactics on Saturday exactly the opposite of what's required at St James Park. Thankfully for Villa fans, their new manager will tighten things up and ensure Villa play in a more crouched position against stronger opponents like Newcastle.

5) Cooper lets old habits creep back in

Nottingham Forest have been much better recently thanks to Steve Cooper's decision to move to an overtly defensive system, dropping everything back into a restrictive 4-5-1 in which nobody presses the man in possession until they are well into the Forest half. This can, of course, make you too passive, and indeed Forest were caught flat-footed for Arsenal's opener in the fifth minute.

However, Forest were only 1-0 down at half-time and Cooper should have kept being patient. Instead, his team opened up in the second period, as old habits returned to see Forest pouring bodies forward and therefore getting caught badly in the transition. Suddenly Arsenal were winning the ball and galloping into open patches of grass, with substitute Reiss Nelson enjoying all that room in the final third.

It was a harsh lesson for Cooper who, using defensive tactics that are against his instinct, must show greater restraint even when his team are a goal down.