Welcome to The Debrief, a Sky Sports column in which Adam Bate uses a blend of data and opinion to reflect on some of the key stories from the latest Premier League matches. This week:

• Xhaka’s key role at Sunderland
• O’Reilly’s impact at Man City
• Amorim’s inflexibility highlighted

Why Xhaka is signing of season

Even before a ball had been kicked, Granit Xhaka to Sunderland looked like it might be the signing of the summer. The feeling was that the midfielder belonged at a Champions League club. Who knows, perhaps next season, that club will be Sunderland.

Victory over Nottingham Forest on Saturday took the Black Cats to 11 points from their first six games. That is not only the best haul by a newly-promoted team in a dozen years but it is Sunderland’s best points tally at this stage of a top-flight season since 1967.

Xhaka was the player of the match, providing the assist for the only goal of the game. In fact, the Switzerland international has assisted each of Sunderland’s last three goals. Only Everton’s Jack Grealish has more assists in the Premier League this season.

The fledgling partnership with Noah Sadiki has been a particular strength of Regis Le Bris’ side, the youngster doing Xhaka’s running. Sadiki covered more ground than anyone else on the pitch against Forest with the tracking data showing that he ran 11.67 kilometres.

That allowed Xhaka to focus on bringing control, using all of his experience to manage the game. Much of the buzz this season has been about Forest’s Elliot Anderson but it was Xhaka who was the outstanding midfielder on the pitch at the City Ground.

He ranks among the top 20 players in the Premier League for touches, interceptions, headed clearances, duels won, possessions won in the middle third, passes completed in the final third, long passes, chipped passes and big chances created. And breathe.

So, while Sadiki is helping Xhaka, who turned 33 on Saturday, it pales in comparison to how he is helping his relatively inexperienced team-mates. The former Bayer Leverkusen man’s leadership skills make others better. “It’s natural for him,” Le Bris told Sky Sports.

“He is very good on the ball, he is really smart, he knows how to manage different situations in real time and he is really important for his leadership. He is a future coach, I think. We need to use him. He is so important for a young squad like ours.”

That is already obvious. Recent history would suggest that success for Sunderland is staying in the Premier League. The early signs are that this team can aim higher. Given Xhaka’s role in making that feel possible, he is the signing of the season so far.

O’Reilly is Man City’s talisman

The introduction of Nico O’Reilly to Manchester City’s starting line-up was a turning point of their season last time around. Even Pep Guardiola, who noted the youngster’s role in that upturn in form, might be surprised to see the same happening this season.

City suffered back-to-back Premier League defeats in August, Guardiola opting to replace the injured Rayan Ait-Nouri with Nathan Ake early on at home to Tottenham. But since O’Reilly’s recall for the Manchester derby, they have been much improved.

It would be five wins from five in all competitions but for Gabriel Martinelli’s stoppage-time equaliser at Arsenal and the change since O’Reilly came in mirrors his record last season when City won 83 per cent of their games with him and only 50 per cent without.

“I think since he started to play, we lost just one game, in the final of the FA Cup against Palace,” said Guardiola on Saturday evening. “We were being defeated all the time. So Nico helped us a lot, improved a lot with his aggressivity, the details, and with the ball.”

Watching their 5-1 win over a Burnley side that stationed Kyle Walker high and wide to provide an aerial target for Martin Dubravka on the restarts, that aggression was clear to see. O’Reilly, at 6ft 4in tall, competed well and also made four tackles for his team.

That was as many as all of his City colleagues combined with 20-year-old O’Reilly also getting forward well, having five touches in the opposition penalty box – which was only bettered by striker Erling Haaland and the two City wingers, Jeremy Doku and Savinho.

O’Reilly has played as an attacking midfielder at age-group level, with talk of him evolving into the holding role, but it is at left-back that he has forced his way into the team and earned a new contract. “I am really pleased,” said Guardiola. “Nico is growing a lot.”

There are other elements to why his presence has helped, most notably shifting Josko Gvardiol inside to partner Ruben Dias. City have conceded six goals in 12 games since April with that pair together. But credit to the youngster for his role in making it happen.

Amorim’s inflexibility exposed

It was impossible not to think of Ruben Amorim’s Manchester United when sat in Vitor Pereira’s press conference on Friday ahead of his team’s trip to Tottenham. The Wolves boss was being asked whether he might switch from a back three to a back four instead.

“I am not here to please myself. I am here to help my players, to help my team, to increase the level of my team, the dynamics, to make all of them comfortable in their roles,” explained Pereira, having seen his side beat Everton in the Carabao Cup playing a back four.

“I am not a coach with fixed ideas, I am someone that is very open to analysis, and to talk about it if we are struggling in the system. If I keep going with the same problems and I don’t try to find solutions, for me, I am not a coach, I am not a manager.”

Pereira duly opted for a back four for the first time in his Premier League managerial career at Tottenham, which may well have surprised Thomas Frank. It certainly did when he made the call to switch back to a five with the game goalless at half-time.

“They changed to a 5-3-2,” said Frank afterwards. “That made it more difficult. Not that we didn’t know they could do it, but of course how do we get the message across to the players?” The element of surprise almost brought Wolves an unlikely victory over Spurs.

While it might feel odd to highlight the tactics of a team rooted to the bottom of the table as an example to Amorim, it is natural to wonder whether the United coach’s unwillingness to adjust is not only making it harder for his players but easier for opponents as well.

In the Premier League, teams are constantly probing to exploit any weakness and managers talk of having to continually evolve to stay one step ahead. The game has visibly changed in style this season, even the best teams having to shift their approach.

But not this United. Keith Andrews’ Brentford knew exactly what to expect. The approach of Amorim is unchanging but with the team still waiting for back-to-back wins under the Portuguese, one suspects results will stay the same too if he cannot adapt.