Moises Caicedo emerges as Chelsea's driving force alongside Enzo Maresca, Gabriel Martinelli's quest for form at Arsenal - The Radar

Welcome to The Radar, a Sky Sports column where Nick Wright combines data and analysis to explore the most important stories in the Premier League. This week:

From tearful teenager to midfield titan
Martinelli's Arsenal struggles examined
A player to watch this weekend

Caicedo thriving under Maresca

Liverpool were Chelsea's main rivals to sign Moises Caicedo from Brighton but he will face another club who tried when Arsenal visit Stamford Bridge on Super Sunday. Having put a difficult first season behind him, the 23-year-old is showing why he was so coveted.

His spectacular equalising goal against Manchester United, volleyed past Andre Onana from outside the box at Old Trafford, propelled his name into the headlines but Caicedo has been excelling all season. "Moi is showing how good he is," said Enzo Maresca.

Chelsea sit fourth going into the weekend, seven places and six points better off than at the same stage of last season. Caicedo has been the driving force, snapping into challenges at the base of midfield and showing his quality on the ball as well as off it.

He is only of only four outfielders, along with Cole Palmer, Nicolas Jackson and Levi Colwill, to have started every Premier League game under Maresca. Only Colwill has played more minutes. It underlines Caicedo's importance to his new head coach.

He featured prominently under Mauricio Pochettino too, of course, starting 20 consecutive Premier League fixtures between December and May. But his £115m price-tag weighed heavily. He was unable to replicate the performance levels shown at Brighton.

That has changed this season. Chelsea, so often overrun in midfield last term, their openness reflected by a total of 67 goals conceded in 38 games, have let in only 12 in 10 this time around.

The improvement is a consequence of limiting opposition chances more effectively. Chelsea are facing fewer shots than last season and giving up fewer expected goals against. Crucially, they are allowing fewer touches in, and passes into, their penalty box.

It owes a lot to the defensive screen provided by the tenacious Caicedo. His combined total of 52 tackles and interceptions, 14 of which came in his dominant displays against Manchester United and Newcastle, is the highest of any Premier League player this season.

Maresca puts his improvement down to time.

"Most of the time in football, one plus one is not two," he said. "Just because he was so good at Brighton, that doesn't mean that when he joins Chelsea he is automatically going to be as good.

"He needs a little bit more time to adapt. Chelsea is a big club, one of the best in the world, so the impact is not easy. When players join Chelsea, it is not automatic."

Maresca's comments called to the mind a conversation last year with Caicedo's old coach at Independiente del Valle in Ecuador, Miguel Angel Ramirez, who fondly recalled the youthful innocence of a player who was prone to crying at harsh treatment in training.

One anecdote involved a tearful reaction to being denied a request for a day off to celebrate his birthday with his family, three hours' drive away from the club's training base. His nickname in Ecuador, 'Niño Moi', or 'The Boy Moi', is another nod to that character.

In hindsight, it is easy to see why his move to Chelsea, completed only a few years later, aged 21, might have taken some getting used to. Going from Ecuador to Brighton was a step up too, of course. But not on the scale of becoming a £115m signing at Chelsea.

Caicedo needed time to acclimatise. But his improvement is down to tactical adjustments too. His heat maps show how his role has changed. Caicedo is less active in the opposition half under Maresca and more focused on performing the duties of a No 6.

The narrower remit means he is seeing less of the ball. His touches and passes are down by roughly 20 per cent this season. But that reduced responsibility in possession, enabled partly by Chelsea's full-backs being asked to tuck into midfield by Maresca, helps to explain his immense defensive contribution.

He continues to contribute offensively, of course. His stunning goal at Old Trafford was the latest reminder that. The quality of his passing has shone through too, most notably with his through-ball assists for Nicolas Jackson against West Ham and Liverpool.

His fortunes contrast with those of fellow £100m midfielder Enzo Fernandez, who has lost his place to Romeo Lavia for what Maresca describes as a lack of physicality. Caicedo, like his new midfield partner, brings those qualities in abundance, and plenty more besides. From boy to man, he is showing them all now.

Arsenal need more from Martinelli

Arsenal's trip to Stamford Bridge will stir fond memories for Gabriel Martinelli. On his first visit to the ground in January 2020, soon after Mikel Arteta's appointment, he underlined his huge potential with an exhilarating solo goal following a run from just outside his own box which left N'Golo Kante scrambling in his wake.

Martinelli remains a livewire, five years on, furiously hard-working and capable of blistering directness. But there is no escaping the decline in the numbers that matter most. Since a stellar 2022/23 campaign, his goals and assists have trended in the wrong direction.

It seemed he might have turned a corner recently, when he produced two goals and two assists in three consecutive Premier League games before an eye-catching display in Europe against Shakhtar Donetsk in which his low effort forced the decisive own goal.

But consistency continues to elude him. A player so clinical at his best too often lacks confidence and conviction in his execution in and around the opposition box.

In his defence, it is no coincidence his best run of the season came when he had a consistent presence behind him at left-back, with Riccardo Calafiori starting seven games in a row before suffering an injury last month. Since then, Arteta has had to chop and change.

That inconsistency has been a theme of the last two seasons.

While Bukayo Saka has mostly benefitted from stability on the opposite flank, with Ben White at right-back and Odegaard on the inside, Martinelli has had to adapt to a revolving cast, both at left-back, where Oleksandr Zinchenko has lost his place, and in the left-sided No 8 role vacated by Granit Xhaka.

The circumstances go some way to explaining Martinelli's struggles. But Arsenal need more, even with Odegaard returning. Stamford Bridge would be a fitting setting for him to deliver again.

Player Radar: Who else to keep an eye on

If Nottingham Forest are to make it four wins in a row when they host Newcastle on Super Sunday, they will need another strong showing from Murillo. The Brazilian has excelled defensively and brings flair to his role too. His total of 31 successful dribbles since the start of last season is the highest of any centre-back.

Live Radar: What's on Sky this weekend?

Brighton host faltering Manchester City on Saturday Night Football, live on Premier League from 5pm ahead of the 5.30pm kick-off time.

On Super Sunday, the final Premier League fixtures before the international break see Nottingham Forest and Newcastle face off at 2pm before Chelsea's meeting with Arsenal at 4.30pm.

Both games are live on Premier League or available to watch with a NOW pass.

Read last week's Radar

Last week's column focused on Nicolas Jackson's rapid progress at Chelsea, the value of Timo Werner's off-the-ball running to Tottenham, and Manchester City's issues defending fast breaks without Kyle Walker or Rodri.