Transfer deadline day was back with a bang.

High-profile names switching clubs, big bucks being exchanged, transfers breaking down and a hashtag demanding the sacking of a high-profile chief executive meant the final day of the Premier League summer transfer window proved rather entertaining.

Here are five of the biggest talking points of the final day of wheeling and dealing until January…

Why did Arsenal want David Luiz?

Transfer deadline day often throws up a deal which leaves some fans of both clubs asking ‘why?’

Chelsea defender David Luiz leaving for London rivals Arsenal – not long after signing a new contract and professing his love for the Blues – might well be one of them.

“It is a bit of a strange one – but it didn’t entirely come out of the blue,” explains BBC Sport correspondent David Ornstein.

“In January 2018 there was some late interest on deadline day from Arsenal for Luiz and since then the Gunners have brought in Unai Emery – who he worked with briefly at Paris St-Germain – while Edu, who knows him from Brazil, is Arsenal’s technical director.”

The departure of club captain Laurent Koscielny to French side Bordeaux on Wednesday sharpened Arsenal’s search for a proven Premier League centre-back.

Former Chelsea midfielder Andy Townsend believes signing Luiz for £8m is “extremely good business” for the Gunners.

“He is exactly the type of centre-half they needed to acquire. I think he is the right fit at this particular juncture for Arsenal,” he said.

“When you think Brighton have taken Adam Webster for £20m from Bristol City, without any Premier League experience or top-flight know-how – and that’s no slight on a very good young player – to get a deal like this done is shrewd.

“There will be a few raised eyebrows but he can be exceptional on his day and I think he is a leader in his own right.”

Why Spurs should not be distraught by Dybala deal collapsing

Tottenham looked on the verge of signing Juventus forward Paulo Dybala when the north London club swooped in after his proposed move to Manchester United collapsed because of his wage demands.

Then, in a classic deadline day twist, the Italian champions decided to pull the plug on the deal, leaving plenty of Spurs fans disappointed not to land what would have been a marquee signing.

On reflection, they may well still see it as a strong summer, with the club-record deal for Tanguy Ndombele followed by the arrivals of England Under-21 winger Ryan Sessegnon and Argentina midfielder Giovani lo Celso. on deadline day.

“Tottenham have had a standout window,” ESPN football journalist Melissa Reddy told BBC Radio 5 Live. “They have made signings in key areas and with pedigree, aligned with the fact they have continuity and consistency.

“They were desperate for a refresh which they now have. All along I had a feeling it would be Manchester City and Liverpool plus the rest – now I think it’s Manchester City and Liverpool, and Tottenham will worry the other two more than any other club.”

Ian Dennis, BBC Radio 5 live’s chief football reporter, added: “I never thought the Dybala deal was going to happen. It was just too expensive and too complicated with his demands and the image rights.

“I think all in all the Tottenham people have delivered the players that Mauricio Pochettino wanted.”

It will be the future of another attacking midfielder, Christian Eriksen, which will now occupy the minds of Spurs fans. He is thought to be keen on a move to Spain and the La Liga transfer window does not close until 2 September.

Does Lukaku exit leave Manchester United short up front?

If football was solely about statistics then Romelu Lukaku probably would not have been sold by Manchester United.

Lukaku, 26, scored 42 goals in 96 games for United but he was still allowed to join Italian side Inter Milan on deadline day – just two years after his £75m move from Everton.

Only seven players have scored more Premier League goals over the past two seasons.

Yet it is telling United manager Ole Gunnar Solskjaer was happy to sanction the move, while plenty of Red Devils supporters – critical of the Belgian’s work-rate and ability to hold up the ball – were hardly furious he was allowed to leave.

United legend Gary Neville questioned Lukaku’s professionalism and commitment to his former club, an emoji waving goodbye to the striker indicating his feelings.

Despite his scoring record, Lukaku found himself overlooked by Solskjaer last season and was left on the bench for several big games.

The United manager, favouring a quicker, more mobile striker, instead went with England international Marcus Rashford and has also talked up Anthony Martial during pre-season, saying the France forward has the “world class attributes” to flourish in a central role.

Added to that is the emergence of 17-year-old Mason Greenwood, who Rashford says has “frightening natural abilities”.

Whether any of these three – or a combination of them – can step up and increase their goal tallies in Lukaku’s absence is the question to which United supporters do not yet know the answer.

“I knew Lukaku was going but I never thought Manchester United would get another forward in,” BBC Sport football reporter Simon Stone said.

“I think the club felt they have already got – for the way Solskjaer wants to play – the forwards they needed.”

How key is Zaha staying for Palace?

“He’s an important player for the club and I’m looking forward to him doing this season what he has done for the past two seasons.”

No wonder Crystal Palace manager Roy Hodgson looked pleased as he confirmed Wilfried Zaha was staying put at Selhurst Park.

Ivory Coast international Zaha, 26, reportedly put in a transfer request as a deadline-day move to Everton looked likely, only for the Toffees to be unable to strike a deal as Palace played hardball over a player who has been instrumental in keeping them up.

The evidence is clear; when Zaha does not play, Palace struggle.

The Eagles talisman has missed just 15 league matches since 1 January, 2017 – and in those games the Eagles have won only six points from a possible 45.

Added to that, Zaha’s pace and trickery is a nightmare for top-flight defenders and has led to him winning 11 penalties over the past three seasons – a tally only bettered by Manchester City forward Raheem Sterling.

Luka Milivojevic – Palace’s precise penalty-taker – will be rubbing his hands with glee…

Is Carroll coming home a gamble for Newcastle?

Andy Carroll leaving Newcastle in a £35m move to Liverpool was one of the big stories of transfer deadline day in January 2011 – and eight-and-a-half years later, his return to St James’ Park is another.

But will the 30-year-old striker be able to shake his injury problems and rediscover the form which made him a Gallowgate darling?

Carroll scored 31 league goals in 80 matches during his first period at the club, including 11 in his final 19 games before his shock departure.

Having completed 90 minutes in just four Premier League matches over the past two seasons, the fear is the Geordie will not be fit enough regularly to make a significant impact at his boyhood club.

“I think for Newcastle that is a no-brainer,” Townsend says.

“Andy knows that when he’s asked to play week in week out his body lets him down. So he has to accept that he is not going to play every week and is happy to affect matches.

“I think he has to have a change of mentality in the way he thinks and the way he prepares. If he is available for 25 games – set yourself a target – it could be a good bit of business.”